RU2786149C2 - Nhe3 binding compounds and methods for phosphate transport inhibition - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: inventions group relates to medicine, namely to therapy, and can be used to inhibit phosphate uptake in the gastrointestinal tract. The method for the invention comprises enterally administering to a patient an effective amount of an NHE3 inhibitor. The use of the invention relates to the use of an NHE inhibitor in the manufacture of a medicament for inhibiting phosphate uptake in the gastrointestinal tract.

EFFECT: use of inventions makes it possible to reduce serum phosphorus and serum creatinine, to reduce urinary phosphorus excretion.

31 cl, 14 tbl, 16 dwg, 10 ex

Description

RELATED APPLICATIONS

According to this application, under 35 U.S.C. § 119(e), claims priority to U.S. Provisional Application 61/888,879, filed October 9, 2013, and U.S. Provisional Application 81/811,613, filed April 12, 2013. All contents of prior applications are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Technical field

The present invention relates to NHE3-binding and/or NHE3-modulating agents having activity as phosphate transport inhibitors, including inhibitors of phosphate transport in the gastrointestinal tract and kidneys, and methods of using them as therapeutic or prophylactic agents.

Description of the field of technology

Patients with inadequate kidney function, hypoparathyroidism, or certain other medical conditions (such as hereditary hyperphosphatemia, Albright's hereditary osteodystrophy, amyloidosis, etc.) often have hyperphosphatemia, or elevated serum phosphate levels (where levels are, for example, greater than about 6 mg /dl). Hyperphosphatemia, especially if it occurs over extended periods of time, leads to severe abnormalities in calcium and phosphorus metabolism, often resulting in secondary hyperparathyroidism, bone disease, and ectopic calcification in the cardiovascular system, joints, lungs, eyes, and other soft tissues. Higher serum phosphorus levels are highly associated with the development of kidney failure, cardiovascular calcification, and mortality in patients with end-stage renal disease (ESRD). High-normal serum phosphorus levels have been associated with cardiovascular events and mortality among people who have chronic kidney disease (CKD) and among those who have normal kidney function (see, for example, Joy et al., J. Manag CAre PhArm., 13(5):397-411 (2007)). The development of kidney disease can be slowed down by reducing phosphate retention. Thus, for patients with kidney failure who present with hyperphosphatemia, and for patients with chronic kidney disease who have serum phosphate levels within the normal range or only slightly elevated, therapy aimed at reducing phosphate retention is beneficial.

For patients who experience hyperphosphatemia, calcium salts have been widely used to bind intestinal phosphate and prevent its absorption. Various types of calcium salts including carbonate, acetate, citrate, calcium alginate, and keto acid salts have been used to bind phosphate. However, these therapies often cause hypercalcemia, a condition that results from the absorption of high amounts of absorbed calcium. Hypercalcemia causes serious side effects such as cardiac arrhythmias, kidney failure, and calcification of the skin and blood vessels. Frequent monitoring of serum calcium levels is required during therapy with calcium-based phosphate binders. Other non-calcium and aluminum phosphate binders, such as sevelamer, a crosslinked polyamine polymer, have disadvantages that include the amount and frequency of administration required to exhibit therapeutic activity. The relatively modest phosphate-binding capacity of these drugs in vivo obliges patients to increase the dose (up to 7 g per day or more). Such amounts have been shown to result in gastrointestinal discomfort such as dyspepsia, abdominal pain and, in some extreme cases, intestinal perforation.

An alternative approach to preventing intestinal phosphate absorption in patients with elevated serum phosphate levels is to inhibit the intestinal transport system that mediates intestinal phosphate uptake. It should be understood that phosphate absorption in the upper intestine is mediated at least in part by a carrier-mediated mechanism that combines phosphate absorption with sodium absorption. Inhibition of intestinal phosphate transport reduces phosphorus overload in the body. In patients with advanced renal disease (eg, stages 4 and 5), phosphorus overload is manifested directly by serum phosphate concentrations above normal levels, ie, hyperphosphatemia. Hyperphosphatemia is directly related to mortality and complications. Inhibition of intestinal phosphate transport reduces serum phosphate concentration and therefore improves outcome in these patients. In patients with stage 2 or 3 chronic kidney disease, phosphorus overload does not necessarily lead to hyperphosphatemia, i.e. phosphate levels remain normal in some patients, but there is a need to reduce or prevent phosphorus overload even in these early stages to avoid associated bone and vascular disorders, and ultimately improve mortality rates. Similarly, inhibition of intestinal phosphate transport would be particularly beneficial in patients who have a disease that can be cured by eliminating intestinal phosphate uptake. Inhibition of phosphate uptake from glomerular filtrate in the kidney would also be beneficial in the treatment of chronic kidney failure. In addition, inhibition of phosphate transport may slow the progression of kidney failure and reduce the risk of cardiovascular events.

While advances have been made in this field, there remains a need for improved phosphate transport inhibitors. The present invention fulfills this need and provides additional benefits.

SUMMARY OF THE INVENTION

The present invention relates generally to NHE3-binding and/or NHE-modulating compounds having activity as phosphate transport inhibitors, including, for example, inhibitors of phosphate transport in the gastrointestinal tract and kidneys, including their stereoisomers, pharmaceutically acceptable salts and prodrugs, and to the use of such compounds for the inhibition of phosphate uptake, and thus the treatment of any of the various conditions or diseases in which modulation of phosphate uptake provides therapeutic benefit.

Embodiments of the present invention include methods for inhibiting phosphate uptake in the gastrointestinal tract or kidneys of a patient requiring phosphate reduction, comprising administering to the patient a compound that binds to NHE3 and is substantially active in the gastrointestinal tract or kidneys to inhibit phosphate transport. ions (Pi) when administered to a patient.

Some embodiments include methods for inhibiting phosphate uptake in the gastrointestinal tract of a patient in whom there is a need to lower phosphate levels, including enterally administering to the patient a substantially systemically non-bioavailable compound that binds to NHE3 and is substantially active in the gastrointestinal tract to inhibit transport phosphate ions (Pi) when administered to a patient. In some embodiments, the method is selected from one or more of: (a) a method for treating hyperphosphatemia, eg, postprandial hyperphosphatemia; (b) a method of treating a kidney disease, such as chronic kidney disease (CKD) or end stage renal disease (ESRD); (c) a method for reducing serum creatinine levels; (d) a method of treating proteinuria; (e) a time delay method for kidney replacement therapy (RRT), such as dialysis; (f) a method for reducing FGF23 levels; (g) a method for reducing the hyperphosphatemic effect of active vitamin D; (h) a method of alleviating hyperparathyroidism, eg secondary hyperparathyroidism; (i) a method for reducing serum parathyroid hormone (PTH); (j) a method for reducing inter-dialysis weight gain (IDWG); (k) a method of alleviating endothelial dysfunction, such as that caused by postprandial serum phosphate; (l) a method of reducing vascular calcification, eg, intima-localized vascular calcification; (m) a method for reducing the level of phosphorus in the urine (3); (n) a method for normalizing serum phosphorus levels; (o) a method of reducing phosphatonic load in an elderly patient; (p) a method of reducing dietary phosphate uptake; (q) a method for reducing renal hypertrophy; (r) a method for reducing cardiac hypertrophy; and (s) a method of treating obstructive sleep apnea.

In some embodiments, the compound is substantially active on the apical side of the epithelium of the gastrointestinal tract to inhibit Pi transport. In some embodiments, the compound does not substantially pass through the epithelium of the gastrointestinal tract.

In some embodiments, upon administration of a compound to a patient, the compound exhibits a maximum concentration found in serum, defined as C _max , that is less than the Pi transport-inhibiting IC ₅₀ concentration of the compound.

In some embodiments, the systemic exposure to the compound is less than 10% pIC ₅₀ at the PD dose, with fecal recovery greater than about 80%, greater than about 90%, or greater than about 95%. In some embodiments, the compound is substantially active in the small intestine to inhibit Pi transport.

In some embodiments, administration to a patient (a) reduces serum phosphate concentrations or levels to about 150% or less of normal serum phosphate levels and/or (b) reduces dietary phosphorus uptake (3) by at least about 10% relative to untreated states. In some embodiments, administration to a patient reduces urinary phosphorus concentrations or levels by at least about 10% relative to the untreated state. In some embodiments, administration to a patient increases fecal excretion phosphate levels by at least about 10% relative to the untreated state.

In some embodiments, the compound is a persistent inhibitor of NHE3-mediated sodium and hydrogen ion antiport. In some embodiments, the compound is substantially active in the gastrointestinal tract to inhibit NHE3-mediated sodium and hydrogen ion antiport when administered to a patient. In some embodiments, the compound is substantially active on the apical side of the epithelium of the gastrointestinal tract to inhibit NHE3-mediated sodium and hydrogen ion antiport. In some embodiments, the compound is substantially active in the colon to inhibit NHE3-mediated sodium and hydrogen ion antiport when administered to a patient.

In some embodiments, persistent inhibition is characterized by the time-dependent inhibitory activity of the compound in an inhibition assay.in vitro NHE3-mediated antiport of sodium and hydrogen ions, with pIC₅₀ connections in fast conditions (pIC_50promp) is essentially comparable to pIC₅₀ connections under constant conditions (pIC_50pers). In some embodiments, persistent inhibition is characterized by the time-dependent inhibitory activity of the compound in an inhibition assay.in vitro NHE3-mediated antiport of sodium and hydrogen ions, and pIC₅₀ connections in fast conditions (pIC_50promp) and under constant conditions (pIC_50pers) is equal to or greater than about 7.0. In some embodiments, the connection has EU₅₀ to increase the output of phosphate ions with feces (EC₅₀P_f) and EU₅₀ to inhibit NHE3-mediated sodium and hydrogen ion antiport (EC₅₀Na), which is determined by the formula EC₅₀P_f = (r)EC₅₀Na, where r is from about 0.7 to about 1.3. In some embodiments, the connection has EU₅₀ to reduce the output of phosphate ions in the urine (EC₅₀P_u) and EU₅₀ to inhibit NHE3-mediated sodium and hydrogen ion antiport (EC₅₀Na), which is determined by the formula EC₅₀P_u = (r)EC₅₀Na, where r is from about 0.7 to about 1.3. In some embodiments, the connection has EU₅₀ to inhibit the transport of phosphate ions (EC₅₀P) and EU₅₀ to inhibit NHE3-mediated sodium and hydrogen ion antiport (EC₅₀Na), which is determined by the formula EC₅₀P = (r)EC₅₀Na, where r is from about 0.7 to about 1.3.

In some embodiments, administration to a patient increases the patient's daily fecal excretion of sodium and/or fluid. In some embodiments, the compound, when administered at a dose resulting in at least about a 10% increase in fecal water content, has C_max, which is less than IC₅₀ for NHE3 less than approximately 10X IC₅₀, or less than approximately 100X IC₅₀.

In some embodiments, the patient has ESRD and administration to the patient (a) reduces serum phosphate concentrations or levels to about 150% or less of normal serum phosphate levels, and (b) reduces interdialysis weight gain (IDWG) by at least approximately 10% relative to the raw state.

In some embodiments, the patient has CKD and administration to the patient (a) reduces FGF23 levels and serum intact parathyroid hormone (iPTH) levels by at least about 10% relative to the untreated state, and (b) reduces blood pressure and proteinuria by at least approximately 10% relative to the raw state.

In some embodiments, the compound is a fickle NHE3 ligand. In some embodiments, the compound has a maximum inhibition of NHE3-mediated sodium and hydrogen ion antiport of less than about 50%, less than about 20%, or less than about 10%, wherein the maximum inhibition is characterized by the inhibitory activity of the compound in an in vitro NHE3-mediated inhibition assay. antiport of sodium and hydrogen ions and refers to states without sodium. In some embodiments, the compound is substantially inactive in the gastrointestinal tract to inhibit NHE3-mediated sodium and hydrogen ion antiport when administered to a patient. In some embodiments, the compound is substantially inactive in the colon to inhibit NHE3-mediated sodium and hydrogen ion antiport.

In some embodiments, the variability is characterized by the time-dependent inhibitory activity of the compound in an inhibition test.in vitro NHE3-mediated antiport of sodium and hydrogen ions, with pIC₅₀ connections in fast conditions (pIC_50promp) is (essentially) greater than pIC₅₀ connections under constant conditions (pIC_50pers). In some embodiments, the variability is characterized by the time-dependent inhibitory activity of the compound in an inhibition test.in vitro NHE3-mediated antiport of sodium and hydrogen ions, and pIC₅₀ connections in fast conditions (pIC_50promp) is equal to or greater than about 7.0, and moreover pIC₅₀ connections under constant conditions (pIC_50pers) is equal to or less than about 6.0. In some embodiments, the connection has EU₅₀ to increase the output of phosphate ions with feces (EC₅₀P_f) and EU₅₀ to inhibit NHE3-mediated sodium and hydrogen ion antiport (EC₅₀Na), which is determined by the formula EC₅₀P_f = (r)EC₅₀Na, and r is from about 0.1 to about 0.5. In some embodiments, the connection has EU₅₀ to reduce the output of phosphate ions in the urine (EC₅₀P_u) and EU₅₀ to inhibit NHE3-mediated sodium and hydrogen ion antiport (EC₅₀Na), which is determined by the formula EC₅₀P_u = (r)EC₅₀Na, and r is from about 0.1 to about 0.5. In some embodiments, the connection has EU₅₀ to inhibit the transport of phosphate ions (EC₅₀P) and EU₅₀ to inhibit NHE3-mediated sodium and hydrogen ion antiport (EC₅₀Na), which is determined by the formula EC₅₀P = (r)EC₅₀Na, and r is from about 0.1 to about 0.5.

In some embodiments, administration to a patient increases the phosphate/sodium ratio in fecal excretion by at least about 10% relative to the untreated state. In some embodiments, administration to a patient increases daily fecal phosphate excretion without substantially modulating stool shape or fecal water content. In some embodiments, administration to a rodent increases the ratio of sodium in the small intestine (Na_SI)/caecum (Na_FROM) by at least about 10% relative to the untreated state.

Also included within the scope of the invention are methods of increasing phosphaturia in a patient in whom there is a need for phosphate reduction, comprising administering to the patient (a) a substantially systemically bioavailable compound, or (b) a substantially systemically non-bioavailable compound by a route other than enteral administration; wherein the compound binds to NHE3 and is substantially active in the kidney to inhibit phosphate ion (Pi) transport when administered to a patient. In some embodiments, the method is selected from one or more of: (a) a method for treating hyperphosphatemia, eg, postprandial hyperphosphatemia; (b) a method of treating a kidney disease, such as chronic kidney disease (CKD) or end stage renal disease (ESRD); (c) a method for reducing serum creatinine levels; (d) a method of treating proteinuria; (e) a time delay method for kidney replacement therapy (RRT), such as dialysis; (f) a method for reducing FGF23 levels; (g) a method for reducing the hyperphosphatemic effect of active vitamin D; (h) a method of alleviating hyperparathyroidism, eg secondary hyperparathyroidism; (i) a method for reducing serum parathyroid hormone (PTH); (j) a method for reducing inter-dialysis weight gain (IDWG); (k) a method of alleviating endothelial dysfunction, such as that caused by postprandial serum phosphate; (l) a method of reducing vascular calcification, eg, intima-localized vascular calcification; (m) a method for reducing the level of phosphorus in the urine (3); (n) a method for normalizing serum phosphorus levels; (o) a method of reducing phosphatonic load in an elderly patient; (p) a method of reducing dietary phosphate uptake; (q) a method for reducing renal hypertrophy; (r) a method for reducing cardiac hypertrophy; and (s) a method of treating obstructive sleep apnea.

In some embodiments, the compound substantially penetrates the epithelium of the gastrointestinal tract. In some embodiments, administration to a patient reduces serum phosphate concentrations or levels to about 150% or less of normal serum phosphate levels. In some embodiments, administration to a patient increases urinary phosphate concentrations or levels by at least about 10% relative to the untreated state.

In some embodiments, the compound has (i) a tPSA of at least about 200 Å ² and a molecular weight of at least about 710 daltons in non-salt form, or (ii) a tPSA of at least about 270 Å ² . In some embodiments, the compound has a tPSA of at least about 250 Å ² , or a tPSA of at least about 270 Å ² , or a tPSA of at least about 300 Å ² , or a tPSA of at least about 350 Å ² , or a tPSA of at least at least about 400 Å ² , or tPSA at least about 500 Å ² . In some embodiments, the compound has a molecular weight of at least about 500 Da, or a molecular weight of at least about 1000 Da, or a molecular weight of at least about 2500 Da, or a molecular weight of at least about 5000 Da.

In some embodiments, the compound has (i) a total of NH and/or OH and/or other potential hydrogen bond donor groups greater than about 5; (ii) the total number of O atoms and/or N atoms and/or other potential hydrogen bond acceptors is greater than about 10; and/or (iii) the Moriguchi distribution ratio is greater than about 10^five or less than about 10. In some embodiments, the compound has a permeability coefficient, P_app, less than about 100×10^-6 cm/s, or less than about 10×10^-6 cm/s, or less than about 1×10^-6 cm/s, or less than about 0.1×10^-6 cm/s.

In some embodiments, the compound has the structure of Formula (I) or (IX):

,

,

in which: NHE denotes an NHE-binding small molecule that includes (i) a group containing a heteroatom, and (ii) a cyclic or heterocyclic skeleton or a carrier group directly or indirectly associated with it, and the heteroatom-containing group is selected from a substituted guanidinyl group and a substituted heterocyclic group which may be fused to a backbone or carrier group to form a fused bicyclic structure; and Z is a group having at least one site for attachment to an NHE-binding small molecule, the resulting NHE-Z molecule having overall physicochemical properties that render it substantially impermeable or substantially systemically non-bioavailable; and E means an integer having a value of 1 or greater.

In some embodiments, the compound is an oligomer, dendrimer, or polymer, and wherein Z is a core having two or more sites for attachment to a plurality of NHE-binding small molecules, either directly or through an L bonding group, wherein the compound has the structure of Formula ( X):

,

,

wherein L is a bond or linker connecting the core to the NHE-binding small molecule and n is an integer of 2 or greater, and wherein each NHE-binding small molecule can be the same or different from the others, or a pharmaceutically acceptable salt thereof.

In some embodiments, the total number of freely rotating bonds in the NHE-Z molecule is at least about 10. In some embodiments, the total number of hydrogen bond donors in the NHE-Z molecule is at least about 5. In some embodiments, the total number hydrogen bond acceptors in an NHE-Z molecule is at least about 10. In some embodiments, the total number of hydrogen bond donors and hydrogen bond acceptors in an NHE-Z molecule is at least about 10. In some embodiments, Log P NHE- The Z-binding compound is at least about 5. In some embodiments, the log P of the NHE-Z-binding compound is less than about 1, or less than about 0. In some embodiments, the backbone is 5-membered or 6- a membered cyclic or heterocyclic group. In some embodiments, the framework is aromatic.

In some embodiments, the backbone of the NHE-binding small molecule is linked to a Z group, wherein the compound has the structure of Formula (II):

in which: Z denotes a Central part having one or more sites for attachment to one or more NHE-binding small molecules, and the resulting NHE-Z molecule has in general physico-chemical properties that make it essentially impermeable or essentially systemically non-bioavailable ; B is a heteroatom-containing group of an NHE-binding small molecule and is selected from a substituted guanidinyl group and a substituted heterocyclic group which can be fused with a Carcass group to form a fused bicyclic structure; The backbone is a cyclic or heterocyclic backbone or carrier group of an NHE-binding small molecule that is linked directly or indirectly to a heteroatom-containing group B and which may be substituted with one or more additional hydrocarbyl or heterohydrocarbyl groups; X is a bond or an intermediate group selected from the group consisting of substituted or unsubstituted hydrocarbyl or heterohydrocarbyl, and in particular substituted or unsubstituted C_1-7 hydrocarbyl or heterohydrocarbyl, and substituted or unsubstituted, saturated or unsaturated, cyclic or heterocyclic groups, which links B and Framework; and D and E are integers, each independently having a value of 1 or greater.

In some embodiments, the NHE-binding small molecule has the structure of Formula (IV):

or a stereoisomer, prodrug or pharmaceutically acceptable salt thereof, wherein: each R_1,R₂, R₃, R_five and R_nine independently selected from H, halogen, -NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H or a bond linking the NHE-binding small molecule to L, provided that at least one is a bond linking the NHE-binding small molecule to L; R_four selected from H, C₁-C₇ alkyl or a bond linking the NHE-linking small molecule to L; R₆ missing or selected from H and C_1-7 alkyl; and Ar1 and Ar2 are independently an aromatic ring or a heteroaromatic ring.

In some embodiments, the NHE-binding small molecule has the following structure:

or a stereoisomer, prodrug or pharmaceutically acceptable salt thereof, wherein: each R_1,R₂ and R₃ independently selected from H, halogen, -NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈independently selected from H or a bond linking the NHE-binding small molecule to L, wherein at least one is a bond linking the NHE-binding small molecule to L.

In some embodiments, the NHE-binding small molecule has one of the following structures:

or a stereoisomer, prodrug or pharmaceutically acceptable salt thereof. In some embodiments, L is a polyalkylene glycol linker. In some embodiments, L is a polyethylene glycol linker. In some embodiments, n = 2.

In some embodiments, the Central part has the following structure:

,

,

in which: X is selected from the group consisting of bond, -O-, -NH-, -S-, C _1-6 alkylene, -NHC(=O)-, -C(=O)NH-, -NHC( =O)NH-, -SO ₂ NH- and -NHSO ₂ -; Y is selected from the group consisting of a bond, optionally substituted C _1-6 alkylene, optionally substituted aryl, optionally substituted heteroaryl, polyethylene glycol linker, -(CH ₂ ) _1-6 O(CH ₂ ) _1-6 - and -(CH ₂ ) _1-6 NY ₁ (CH ₂ ) _1-6 -; and Y ₁ is selected from the group consisting of hydrogen, optionally substituted C _1-6 alkyl, optionally substituted aryl, or optionally substituted heteroaryl, or a pharmaceutically acceptable salt thereof.

In some embodiments, the Central part is selected from the group consisting of:

In some embodiments, the compound has the following structure of Formula (I-H):

or a stereoisomer, prodrug or pharmaceutically acceptable salt thereof, wherein: (a) n is an integer of 2 or greater; (b) Core means a core having two or more sites for attachment to two or more NHE-linked small molecules; (c) L is a bond or linker connecting the Core to two or more NHE-binding small molecules; and (d) NHE is an NHE-binding small molecule having the following structure of Formula (XI-H):

,

,

in which: B is selected from the group consisting of aryl and heterocyclyl; every R_five independently selected from the group consisting of hydrogen, halogen, optionally substituted with C_1-4alkyl, optionally substituted with C_1-4alkoxy, optionally substituted with C_1-4thioalkyl, optionally substituted heterocyclyl, optionally substituted heterocyclylalkyl, optionally substituted aryl, optionally substituted heteroaryl, hydroxyl, oxo, cyano, nitro, -NR₇R₈, -NR₇C(=O)R₈, -NR₇C(=O)OR₈, -NR₇C(=O)NR₈R_nine, -NR₇SO₂R₈, -NR₇S(O)₂NR₈R_nine, -C(=O)OR₇, -C(=O)R₇, -C(=O)NR₇R₈, -S(O)_1-2R₇ and -SO₂NR₇R₈, and R₇, R₈ and R_nine independently selected from the group consisting of hydrogen, C_1-4alkyl or a bond linking the NHE-binding minor half to L, provided that at least one is a bond linking the NHE-binding minor half to L; R₃ and R_four independently selected from the group consisting of hydrogen, optionally substituted with C_1-4alkyl, optionally substituted cycloalkyl, optionally substituted cycloalkylalkyl, optionally substituted aryl, optionally substituted aralkyl, optionally substituted heterocyclyl and optionally substituted heteroaryl; or R₃ and R_four form, together with the nitrogen to which they are attached, optionally substituted 4-8 membered heterocyclyl; and every R₁ independently selected from the group consisting of hydrogen, halogen, optionally substituted with C_1-6alkyl and optionally substituted C_1-6alkoxy. In some embodiments, n=2. In some embodiments, L is a polyalkylene glycol linker. In some embodiments, L is a polyethylene glycol linker.

In some embodiments, the Central part has the following structure:

in which: X is selected from the group consisting of bond, -O-, -NH-, -S-, C _1-6 alkylene, -NHC(=O)-, -C(=O)NH- -NHC(= O)NH-, -SO ₂ NH-, and -NHSO ₂ -; Y is selected from the group consisting of a bond, optionally substituted C _1-6 alkylene, optionally substituted aryl, optionally substituted heteroaryl, polyethylene glycol linker, -(CH ₂ ) _1-6 O(CH ₂ ) _1-6 - and -(CH ₂ ) _1-6 NY ₁ (CH ₂ ) _1-6 -; and Y ₁ is selected from the group consisting of hydrogen, optionally substituted C _1-8 alkyl, optionally substituted aryl, or optionally substituted heteroaryl, or a pharmaceutically acceptable salt thereof.

In some embodiments, the Central part is selected from the group consisting of

In some embodiments, the NHE-binding small molecule has the following structure of Formula (XII-H):

,

,

in which: each R₃ and R_four independently selected from the group consisting of hydrogen and optionally substituted C_1-4alkyl, or R₃ and R_four, together with the nitrogen to which they are attached, form, if necessary, a substituted 4-8 membered heterocyclyl; every R₁ independently selected from the group consisting of hydrogen, halogen, C_1-6alkyl and C_1-6haloalkyl; and R_five selected from the group consisting of -SO₂-NR₇- and -NHC(=O)NH-, and R₇ stands for hydrogen or C_1-4alkyl.

In some embodiments, R₃ and R_four, together with the nitrogen to which they are attached, form, if necessary, a substituted 5 or 6 membered heterocyclyl. In some embodiments, the optionally substituted 5- or 6-membered heterocyclyl is pyrrolidinyl or piperidinyl. In some embodiments, the optionally substituted 5 or 6 membered heterocyclyl is pyrrolidinyl or piperidinyl, each of which is substituted with at least one amino or hydroxyl. In some embodiments, R₃ and R_four independently denote C_1-4alkyl. In some embodiments, R₃ and R_four stands for methyl. In some embodiments, each R₁ independently selected from the group consisting of hydrogen or halogen. In some embodiments, each R₁ independently selected from the group consisting of hydrogen, F and Cl.

In some embodiments, the compound has the following structure of Formula (I-I):

or a stereoisomer, prodrug or pharmaceutically acceptable salt thereof, wherein: (a) NHE is an NHE-binding small molecule having the following structure of Formula (A-I):

in which: each R₁, R₂, R₃, R_five and R_nine independently selected from H, halogen, -NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H, C_1-6alkyl, -C_1-6alkyl-OH or a bond linking the NHE-binding small molecule to L, provided that at least one is a bond linking the NHE-binding small molecule to L; R_four selected from H, C₁-C₇ alkyl or a bond linking the NHE-linking small molecule to L; R₆ missing or selected from H and C₁-C₇ alkyl; and Ar1 and Ar2 are independently an aromatic ring or a heteroaromatic ring; (b) Core means the Core having the following structure of Formula (B-I):

,

,

in which: X is chosen from C(X₁), N and N(C_1-6alkyl); X₁selected from hydrogen, optionally substituted alkyl, -NX_aX_b, -NO₂, -NX_c-C(=O)-NX_c-X_a, -C(=O)NX_c-X_a, -NX_c-C(=O)-X_a, -NX_c-SO₂-X_a, -C(=O)-X_a and -OX_a, every X_a and X_b independently selected from hydrogen, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted cycloalkylalkyl, optionally substituted heterocyclyl, optionally substituted heterocyclylalkyl, optionally substituted aryl, optionally substituted aralkyl, optionally substituted heteroaryl and optionally substituted heteroarylalkyl; Y stands for C_1-6alkylene; Z is selected from -NZ_a-C(=O)-NZ_a-, -C(=O)NZ_a-, -NZ_a-C(=O)- and heteroaryl when X is CX₁; Z is selected from -NZ_a-C(=O)-NZ_a-, -NZ_a-C(=O)- and heteroaryl when X is N or N(C_1-6alkyl); and each X_c and Z_aindependently selected from hydrogen and C_sixteenalkyl; and (c) L is a bond or linker connecting the Core to NHE-binding small molecules.

In some embodiments, the NHE-binding small molecule has the following structure:

in which: each R₁, R₂ and R₃ independently selected from H, halogen, -NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H, C_1-6alkyl, -C_1-6alkyl-OH or a bond linking the NHE-binding small molecule to L, provided that at least one is a bond linking the NHE-binding small molecule to L.

In some embodiments, the NHE-binding small molecule has one of the following structures:

In some embodiments, L is a polyalkylene glycol linker. In some embodiments, L is a polyethylene glycol linker. In some embodiments, X is C(X₁). In some embodiments, each X_c stands for hydrogen. In some embodiments, X is N. In some embodiments, each Z_a stands for hydrogen.

In some embodiments, the compound has the structure of Formula (II-I):

or a stereoisomer, prodrug or pharmaceutically acceptable salt thereof, wherein: (a) NHE is an NHE-binding small molecule of Formula (A-I):

in which: each R₁, R₂, R₃, R_five and R_nine independently selected from H, halogen, -NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H, C_1-6alkyl, -C_1-6alkyl-OH or a bond linking the NHE-binding small molecule to L, provided that at least one is a bond linking the NHE-binding small molecule to L; R_four selected from H, C₁-C₇ alkyl or a bond linking the NHE-linking small molecule to L; R₆ missing or selected from H and C₁-C₇ alkyl; and Ar1 and Ar2 are independently an aromatic ring or a heteroaromatic ring; (b) Core means the core having the following structure of Formula (C-I):

in which: W is selected from alkylene, polyalkylene glycol, -C(=O)-NH-(alkylene)-NH-C(=O)-, -C(=O)-NH-(polyalkylene glycol)-NH-C(= O)-, -C(=O)-(alkylene)-C(=O)-, -C(=O)-(polyalkylene glycol)-C(=O)- and cycloalkyl; X is N; Y stands for C_1-6alkylene; Z is selected from -NZ_a-C(=O)-NZ_a-, -C(=O)NZ_a-, -NZ_a-C(=O)- and heteroaryl; every Z_a independently selected from hydrogen and C_1-6alkyl; and (c) L is a bond or linker connecting the Core to NHE-binding small molecules.

In some embodiments, the NHE-binding small molecule has the following structure:

in which: each R₁, R₂ and R₃ independently selected from H, halogen, -NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H, C_1-6alkyl, -C_1-6alkyl-OH or a bond linking the NHE-binding small molecule to L, provided that at least one is a bond linking the NHE-binding small molecule to L.

In some embodiments, the NHE-binding small molecule has one of the following structures:

In some embodiments, the compound is selected from a Table E3 or Table E4 compound, or a pharmaceutically acceptable salt thereof.

In a private embodiment, the connection is:

or a pharmaceutically acceptable salt thereof.

In a private embodiment, the connection is:

Some methods further include administering one or more additional biologically active agents. In some embodiments, the compound and one or more additional biologically active agents are administered as part of a single pharmaceutical composition. In some embodiments, the compound and one or more additional biologically active agents are administered as individual pharmaceutical compositions. In some embodiments, the individual pharmaceutical compositions are administered sequentially. In some embodiments, the individual pharmaceutical compositions are administered simultaneously.

In some embodiments, the additional biologically active agent is selected from vitamin A D₂ (ergocalciferol), vitamin D₃ (cholecalciferol), active vitamin D (calcitriol), and active vitamin D analogs (eg doxercalciferol, paricalcitol).

In some embodiments, the additional biologically active agent is a phosphate binder. In some embodiments, the phosphate binder is selected from the group consisting of sevelamer (e.g., Renvela® (sevelamer carbonate), Renagel® (sevelamer hydrochloride)), lanthanum carbonate (e.g., Fosrenol®), calcium carbonate (e.g., Calcichew®, Titralac®), calcium acetate (eg PhosLo®, Phosex®), calcium acetate/magnesium carbonate (eg Renepho®, OsvAren®), MCI-196, iron citrate (eg Zerenex™), magnesium iron hydroxycarbonate (eg , Fermagate™), alumina hydrate (eg Alucaps®, Basaljel®), APS 1585, SBR-759 and PA-21.

In some embodiments, the additional biologically active agent is a NaPi2b inhibitor. In some embodiments, the additional biologically active agent is niacin or nicotinamide.

In some embodiments, the compound or composition is administered orally. In some embodiments, the compound or composition is administered orally once a day.

These and other aspects of the invention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE FIGURES

Figures 1A-B show the effects of test compounds on reducing phosphate uptake in normal functioning rats (see Example 3). Figure 1A shows that Conn. 004, a non-permanent inhibitor of NHE3, reduced Pi uptake as much as a permanent inhibitor such as Comm. 003. Figures 1B-C show that Conn. 003 significantly reduced Pi uptake in the presence of Glucose/Ca ( 1B ) and Ca ( 1C ).

Figure 2 shows a study design for testing the activity of compounds in a rat model of uremia-associated vascular calcification.

Figures 3A-F show basal body weight ( 3A ) and serum parameters (serum phosphorus ( 3B ); serum calcium ( 3C ); serum creatinine ( 3D ); blood urea nitrogen ( 3E-F )) in a rat model of uremia-associated calcinosis. vessels.

Figures 4A-F show the effects of the test compound on serum parameters (plasma creatinine ( 4A ); blood urea nitrogen ( 4B ); plasma protein ( 4C ); plasma phosphorus ( 4D ); plasma calcium ( 4E ); and plasma FGF23 ( 4F ) ) in a rat model of uremia-associated vascular calcification. These results indicate that the test compounds significantly reduce plasma creatinine, plasma phosphorus and plasma FGF23. The test compound also significantly increases plasma protein and slightly increases plasma calcium.

Figure 5 shows the effects of the test compound on the end weight of the heart and kidneys in a rat model of uremia-associated vascular calcification. Administration of the test compound significantly reduced the organ weight/body weight values for heart and kidney.

Figures 6A-B show the effects of the test compound on terminal creatinine clearance (C _Cr ) and plasma aldosterone levels in a rat model of uremia-associated vascular calcification. Test compound administration maintained creatinine clearance compared to vehicle alone and also significantly increased plasma aldosterone.

Figures 7A-B show the effects of the test compound on terminal vascular and soft tissue calcification in a rat model of uremia-associated vascular calcification. Administration of the test compound significantly reduced the mineral content of phosphorus and calcium in the stomach and aorta.

Figure 8A shows a study design to test the activity of compounds in a rat model of adenine-induced uremia. Figures 8B-C show that the test compound significantly reduces serum phosphorus and serum creatinine at early time points in this acute kidney injury model.

Figures 9A-B show cumulative organ weights from week three in a rat model of adenine-induced uremia. The administration of the test compound showed a tendency to decrease the change in the heart and kidneys.

Figures 10A-B show tissue mineralization data from week three in a rat model of adenine-induced uremia. Administration of the test compound reduced cardiac and renal calcification at the highest dose (5 mpk).

Figure 11A shows a study design for testing the activity of compounds in a dietary salt-induced partial renal ablation model of chronic kidney disease (CKD). Figure 11B shows the effects of the test compound on urinary phosphorus excretion.

Figure 12 shows a study design for testing the activity of a test compound on urinary phosphate and calcium excretion in rats.

Figures 13A-D show that administration of the test compound reduced both urinary phosphorus mass and urinary calcium mass compared to a vehicle-only control. Increasing test compound dosages also significantly reduced urinary phosphorus mass relative to Renvela® at 48 mg/kg.

Figures 14A-B show the mean daily fecal excretion of Na (14A; +/- SE) and phosphorus (14B; +/-). The excretion data were averaged over a 7 day treatment period (Day 1 - Day 7) and presented as mEq/day (see Example 8). Statistical analysis was performed using one-way ANOVA; (*); p < 0.05, (**); p < 0.01, (***); p < 0.001.

Figures 15A-C show the mean daily fecal excretion of phosphorus (15A; +/- SE) and the mean daily urinary excretion of sodium (15B; +/- SE) and phosphorus (15C; +/-) (see Example 9 ). Statistical analysis was performed using one-way ANOVA; (*); p < 0.05, (**); p < 0.01, (***); p < 0.001.

Figures 16A-B show the mean daily fecal sodium excretion (16A; +/- SE) and the mean daily fecal phosphorus excretion (16B; +/- SE) (see Example 10). Statistical analysis was performed using one-way ANOVA followed by Tukey's multiple comparison test; (*); p < 0.05, (**); p < 0.01 (***); p < 0.001 vs pre-dose.

DETAILED DESCRIPTION

In the following description, some specific details are set forth in order to provide a thorough understanding of the various embodiments of the invention. However, the person skilled in the art will understand that the invention can be practiced without these details.

Unless the context otherwise requires, throughout the text of this specification and the claims, the word "comprises" and variations of it, such as "include" and "comprising", are to be considered in an open, inclusive sense, that is, as, "including, but not limited."

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the present invention. Thus, the occurrences of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment. In addition, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Some embodiments relate to the surprising discovery that intestinal phosphate absorption in patients with elevated serum phosphate levels can be limited, and preferably substantially prevented, by NHE3-binding and/or NHE3-modulating agents with inhibition of the intestinal transport system that mediates phosphate uptake in the intestine. It has also surprisingly been found that such NHE3 binding and/or NHE3 modulating agents can inhibit the renal transport system that mediates phosphate uptake in the kidney.

In some aspects, inhibition of phosphate uptake in the gastrointestinal tract may be achieved by administering certain compounds, and/or pharmaceutical compositions comprising them, which may preferably be designed such that little, or substantially none, of the compounds is absorbed into the blood flow (ie, designed to be non-systemic or essentially non-systemic). In this respect, the compounds have features that result in low systemic availability or essentially no systemic availability when administered enterally, including orally. In other words, the compounds are not absorbed into the bloodstream at significant levels and therefore have no activity there, but instead their activity is localized essentially to the GI tract.

Therefore, in some illustrative embodiments, as further described herein, the compounds of the invention typically require a combination of structural and/or functional features related to or contributing to their activity in the GI tract and/or their actual non-systemic bioavailability. Such features may include, for example, one or more of (i) tPSA and/or MBT specific values (e.g., at least about 190 Ų and/or at least about 736 Daltons, respectively), (ii) specific levels of fecal recovery of the compound and/or its metabolites after administration (eg, greater than 50% in 72 hours); (iii) specific amounts of NH and/or OH and/or potential hydrogen bond donor groups (eg, greater than about five); (iv) specific numbers of rotatable bonds (eg, greater than about five); (iv) specific permeability characteristics (for example, P_app less than about 100×10^-6 cm/s); and/or any of a variety of other features and characteristics, as described here.

The essentially non-systemic compounds described herein provide numerous benefits in the treatment of the GI tract and other disorders. For example, the compounds are active against a phosphate transporter located apically in the gut and do not substantially reach other phosphate transporters expressed in other tissues and organs. Because NHE3 is expressed in cells of many systemic tissues or organs, the use of NHE3-binding or modulating agents may raise questions about general actions that are targeted or untargeted. These particular compounds do not raise such concerns due to their limited systemic availability.

As noted above, some embodiments relate to the discovery that phosphate absorption from glomerular filtrate in the kidneys of patients with elevated serum phosphate levels can be limited, and preferably substantially prevented, through inhibition of the renal tubular transport system that mediates phosphate uptake in the kidney. In some aspects, inhibition of renal phosphate uptake can be achieved by administering the otherwise substantially systemically non-bioavailable compound described herein in a route that may preclude enteral or enteric administration, i.e., a route that may preclude gastrointestinal administration. Non-limiting examples include parenteral administration, such as intravenous, intra-arterial, intramuscular and subcutaneous administration, among others described here and known in the art.

In some aspects, inhibition of phosphate uptake in the kidneys can be achieved by administering certain compounds, and/or pharmaceutical compositions comprising them, which can be preferably designed such that the majority of the compound is absorbed into the circulation (i.e., designed to be systemic or essentially systemic). In this regard, the compounds have features that provide systemic availability, including oral availability. In other words, the compounds are absorbed into the bloodstream at significant levels and therefore exhibit most, if not all of their activity, systemically, eg, within organs such as the kidney, relative to the localization of their activity substantially within the GI tract. Therefore, in some embodiments, especially for targeting systemic tissues via oral or other form of enteral administration, the compounds described herein may have a combination of structural and/or functional features related to or contributing to their substantial systemic bioavailability. Functional features include, for example, whether the compound is substantially permeable through the epithelium of the gastrointestinal tract, including the mouth, esophagus, stomach, upper intestine, lower intestine, etc.

As described in more detail below, phosphate absorption in the upper intestine is mediated, at least in part, by a carrier-mediated mechanism that couples phosphate absorption to sodium absorption. Renal phosphate transport is mediated at least in part by the activity of the sodium-dependent phosphate transporters, Npt2a, Npt2c and PiT-2, present within the membrane of the apical brush border of the proximal tubule. Accordingly, inhibition of intestinal or renal phosphate transport will reduce the body's phosphorus overload.

In patients with advanced renal disease (eg, stages 4 and 5), phosphorus overload manifests itself directly in serum phosphate concentrations above normal levels, ie, hyperphosphatemia. Hyperphosphatemia is directly related to mortality and complications. Inhibition of intestinal or renal phosphate transport reduces serum phosphate levels and therefore improves outcome in these patients. In patients with chronic kidney disease in stages 2 and 3, phosphorus overload does not necessarily lead to hyperphosphatemia, i.e. patients' phosphate levels remain normal, but there is a need to reduce phosphorus overload even in these early stages to avoid associated bone disorders and vessels, and ultimately improve mortality rates.

Inhibition of intestinal phosphate transport will be particularly beneficial in patients who have a disease that can be treated by eliminating intestinal phosphate uptake. Likewise, inhibition of phosphate absorption from glomerular filtrate within the kidneys would also be beneficial for the treatment or prevention of chronic kidney failure and other disease states of the kidneys. In addition, inhibition of phosphate transport may slow the progression of kidney failure and reduce the risk of cardiovascular events, among other diseases or conditions associated with a need to lower phosphate levels.

I. Compounds that inhibit phosphate transport

Embodiments of the present invention relate generally to the discovery that NHE3 binding and/or NHE3 modulating compounds inhibit the transport or uptake of phosphate ions (Pi) in tissues such as the gastrointestinal tract and/or kidneys. The Pi transport inhibitory activity of a compound in a given tissue will depend in general, for example, on the systemic bioavailability or systemic non-bioavailability of the compound, the route of administration, or any combination thereof.

Accordingly, embodiments of the present invention include compounds that bind to and/or modulate NHE3 (e.g., NHE inhibitors) and are substantially active in inhibiting Pi transport or uptake, e.g., in a human, animal model, and/or or in a biochemical assay. cell based.

In some embodiments, the compound binds to NHE3. In these and related embodiments, a compound is said to "bind" or "specifically binds" to the NHE3 protein if it reacts at a detectable level with the protein and, if appropriate, does not react in a detectable, statistically significant manner with unrelated proteins. in similar conditions. In some illustrative embodiments, the compound may have a binding "affinity" (for example, as measured by a dissociation constant, or K_d) to NHE3 protein about or less than about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 nM.

In some embodiments, one or more of the compounds described herein, when administered alone or in combination with one or more additional pharmaceutically active compounds or agents to a patient, or when measured in an animal model or in a cell-based test, may have an IC₅₀ in terms of Pi transport or uptake inhibition, about or less than about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 nM. In some embodiments, one or more of the compounds detailed herein, when administered alone or in combination with one or more additional pharmaceutically active compounds or agents to a patient or as measured in an animal model or in a cell-based test, may have pIC₅₀ in relation to Pi transport or uptake inhibition about or greater than about 6.0, 6.05, 6.1, 6.15, 6.2, 6.25, 6.3, 6.35, 6.4, 6, 45, 6.5, 6.55, 6.6, 6.65, 6.7, 6.75, 6.8, 6.85, 6.9, 6.95, 7.0, 7.05, 7.1, 7.15, 7.2, 7.25, 7.3, 7.35, 7.4, 7.45, 7.5, 7.55, 7.6, 7.65. 7.7, 7.75, 7.8, 7.85, 7.9, 7.95, 8.0, 8.05, 8.1, 8.15, 8.2, 8.25, 8, 3, 8.35, 8.4, 8.45, 8.5, 8.55, 8.6, 8.65, 8.7, 8.75, 8.8, 8.85, 8.9, 8.95 or 9.0.

As part of the invention IC₅₀ is defined as a quantitative indicator indicating the concentration of a compound at which 50% of its maximum inhibitory effect is observed, for example, in a human, in an animal model and/or or in a cell-based biochemical test. pIC₅₀ refers to the inverse logarithm IC₅₀ (or pIC₅₀ = -log (IC₅₀) (see Selvaraj et al., Current Trends in Biotechnology and Pharmacy. 5: 1104-1109, 2011). Tests for measuring the activity of phosphate transport or uptake inhibitors are described in the accompanying Examples.

In order to inhibit the transport or uptake of Pi in the gastrointestinal tract and to treat associated conditions in a patient for whom there is a need to reduce phosphate levels, embodiments of the present invention generally use a compound that is essentially systemically non-bioavailable. Such compounds are preferably formulated or suitable for enteral administration, including oral administration. Examples of a substantially systemically non-bioavailable compound and their associated features are provided elsewhere herein. In these and related embodiments, administration of a compound to a patient reduces one or more of serum phosphate concentrations or levels, dietary phosphorus, and/or urinary phosphate concentrations or levels. In some embodiments, serum phosphate concentrations or levels in a patient with hyperphosphatemia are reduced to about or less than about 150%, 145%, 140%, 135%, 130%, 125%, 120%, 115%, 110%, 105% or 100% (normalized) normal serum phosphate levels (healthy patient, eg 2.5-4.5 mg/dL or 0.81-1.45 mmol/L for an adult). In some embodiments, dietary phosphorus uptake is reduced by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or more relative to the untreated state. In some embodiments, urinary phosphate concentrations or levels are reduced by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% or more, preferably about 20%, 30%, 40%, 50% or 60%, relative to the untreated state. In some embodiments, administration of a compound to a patient increases faecal excretion phosphate levels by at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100 %, 200% or more relative to the raw state.

For the inhibition of Pi transport or uptake in the kidney and the treatment of associated conditions in a patient for whom there is a need for phosphate reduction, embodiments of the present invention typically use compounds that are substantially systemically bioavailable, optionally administered by any route of administration, or substantially systemically non-bioavailable. the compounds described herein are preferably administered by administration which excludes enteral administration. In these and related embodiments, administration of the compound reduces serum phosphate concentrations or levels in a patient with hyperphosphatemia to about or less than about 150%, 145%, 140%, 135%, 130%, 125%, 120%, 115%, 110 %, 105%, or 100% (normalized) normal serum phosphate levels (healthy patient, eg 2.5-4.5 mg/dL or 0.81-1.45 mmol/L for an adult). In some embodiments, administration of a compound to a patient increases urinary phosphate concentrations or levels by at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% or more relative to the raw state.

In some embodiments, the NHE3 binding compounds of the present invention are further characterized by their activity for NHE3-mediated sodium and hydrogen ion antiportation. For example, certain compounds are substantially active in inhibiting NHE3-mediated sodium and hydrogen ion antiport. Such "dual activity" compounds can thus be used to inhibit gastrointestinal and/or renal transport or uptake of both phosphate and sodium. In other embodiments, the compounds are substantially inactive in inhibiting NHE3 mediated sodium and hydrogen ion antiport. Such "monoactive" compounds can be used to inhibit phosphate uptake in the gastrointestinal tract and/or in the kidneys without significantly modulating sodium transport or uptake in either tissue.

Without wishing to be bound by any theory, it is believed that compounds that are "permanent" inhibitors of NHE3 (e.g., compounds that bind to NHE3 and inhibit NHE3-mediated sodium and hydrogen ion antiportation under both "fast" conditions and under "permanent" conditions) are essentially active in tissues, inhibiting both Pi transport and NHE3-mediated sodium and hydrogen ion antiport. In contrast, non-persistent NHE3 ligands (e.g., compounds that bind to or otherwise interact with NHE3 and can inhibit NHE3-mediated sodium and hydrogen ion antiport under "fast" conditions but do not substantially inhibit it under "persistent" conditions) are thought to be active. in tissues for inhibition of Pi transport, but essentially inactive in tissues for inhibition of NHE3-mediated sodium and hydrogen ion antiport. Some characteristics of these compounds are described below.

A. Dual Activity Compounds

Some embodiments relate to NHE3 binding and/or NHE3 modulating compounds that inhibit both phosphate ion (Pi) transport and NHE3 mediated sodium and hydrogen ion antiport. These and related embodiments include, for example, compounds that are substantially active in the gastrointestinal tract and/or kidneys to inhibit Pi transport and NHE3-mediated sodium and hydrogen ion antiport when administered to a patient. In particular embodiments, the compounds are substantially active on the apical side of the epithelium of the gastrointestinal tract (eg, when administered enterally) to inhibit NHE3-mediated sodium and hydrogen ion antiport. Also included are compounds that are substantially active in the colon (e.g., caecum, ascending colon, transverse colon, descending colon, sigmoid colon) in inhibiting NHE3-mediated sodium and hydrogen ion antiport when administered to a patient.

In some aspects, dual activity compounds are characterized by their "persistent" binding to NHE3 and inhibition of NHE3-mediated sodium and hydrogen ion antiport, ie, their "persistent inhibition" of NHE-mediated sodium and hydrogen ion antiport. In particular aspects, persistent inhibition is characterized by the time-dependent inhibitory activity of a compound in an in vitro NHE3-mediated sodium and hydrogen ion antiport inhibition assay, e.g. PNAS USA (1984) 81 (23): 7436-7440; and Examples 1-2).

Permanent conditions include, for example, those where the test compound is pre-incubated with the cells, for example, for about 10, 20, 30, 40, 50, 60, 80, 100, 120 minutes or more and washed until the intracellular pH is lowered and tested for NHE3-mediated restoration of neutral intracellular pH. A post-incubation wash may be performed, for example, for about 10, 20, 30, 40, 50, 60, 80, 100, 120 minutes or more before lowering the intracellular pH and testing for NHE3-mediated restoration of neutral intracellular pH. Under certain constant conditions, the test compound is pre-incubated with the cells for the desired time and then washed out of the cell medium, a buffer is added to lower the intracellular pH (e.g., incubated for about 10, 20, 30, 40, 50, or 60 minutes, or more ), and NHE3-mediated restoration of neutral intracellular pH is initiated by the addition of an appropriate buffer without test compound.

Fast conditions include, for example, those where the test compound is incubated with the cells during testing for NHE3-mediated intracellular neutral pH recovery, ie, the compound is not washed out before or during the initiation of intracellular pH recovery. Under some rapid conditions, a buffer is added to lower the intracellular pH (e.g., incubated for about 10, 20, 30, 40, 50, or 60 minutes or more), and NHE3-mediated restoration of a neutral intracellular pH is initiated by adding an appropriate buffer that contains tested connection. In one example cell-based assay, intracellular pH recovery can be measured, for example, by monitoring pH-sensitive changes in marker fluorescence normalized to pH-insensitive marker fluorescence. Examples of markers include bis(acetoxymethyl)-3,3'-(3',6'-bis(acetoxymethoxy)-5-((acetoxymethoxy)carbonyl)-3-oxo-3H-spiro[isobenzofuran-1,9'-xanthene ]-2',7'-diyl)dipropanoate (BCECF).

In some aspects, the compound with dual activity is characterized by time-dependent inhibitory activity of the compound inin vitro test of inhibition of NHE3-mediated antiport of sodium and hydrogen ions, and pIC₅₀ connections in fast conditions (pIC_50promp) is essentially comparable to pIC₅₀ connections under constant conditions (pIC_50pers). Essentially comparable includes, for example, where pIC values_50promp and pIC_50pers are within approximately 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. In private aspects pIC_50promp and pIC_50pers are about or at least about 7.0, including about or at least about 6.5, 6.55. 6.6, 6.65, 6.7. 6.75, 6.8, 6.85, 6.9, 6.95, 7.0, 7.05, 7.1, 7.15, 7.2, 7.25, 7.3, 7, 35, 7.4, 7.45, 7.5, 7.55, 7.6, 7.65. 7.7, 7.75, 7.8, 7.85, 7.9, 7.95, 8.0, 8.05, 8.1, 8.15, 8.2, 8.25, 8, 3, 8.35, 8.4, 8.45, 8.5, 8.55, 8.6, 8.65, 8.7, 8.75, 8.8, 8.85, 8.9, 8.95 or 9.0. In some aspects, IC₅₀ connections in fast conditions (IC_50promp) is essentially comparable to IC₅₀ connections under constant conditions (IC_50pers). Essentially comparable includes, for example, one where the values IC_50promp and IC_50pers is within approximately 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. In private aspects IC_50promp and IC_50peR_e are about or less than about 0.3, 0.2, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, 0.009, 0.008, 0.007, 0.006, 0.005, 0.004, 0.003, 0.002, or 0.001 mM, or range from about 0.001-0.3, 0.001-0.2, 0.001-0.1, 0.001-0, 05, 0.001-0.01, 0.001-0.005 mM, or range from approximately 0.005-0.3, 0.005-0.2, 0.005-0.1, 0.005-0.05, 0.005-0.01, or range from about 0.01-0.3, 0.01-0.2, 0.01-0.1, or 0.01-0.05 mM, or a range of about 0.1-0.3 or 0.1- 0.2 mm.

In some aspects, dual activity compounds are characterized by their relative activity in inhibiting phosphate transport and inhibiting NHE3-mediated sodium and hydrogen ion antiport. For example, when administered enterally to a patient requiring phosphate reduction, some compounds may have an EC₅₀ in relation to increased excretion of phosphate ions with feces (EC₅₀P_f) and EU₅₀ with respect to inhibition of NHE3-mediated sodium and hydrogen ion antiport (EC₅₀Na), which is determined by the formula EC₅₀P_f = (r)EC₅₀Na, in which r is from about 0.6 to about 1.5, preferably from about 0.7 to about 1.3 or from about 0.6, 0.65, 0.7, 0.75, 0.8 , 0.85, 0.9, 0.95, 1.0, 1.1, 1.2, 1.3, 1.4, or 1.5, including all ranges in between. In some embodiments, for example, when administered enterally to a patient requiring phosphate reduction, some compounds may have EU₅₀ in relation to a decrease in the output of phosphate ions in the urine (EC₅₀P_u) and EU₅₀ with respect to inhibition of NHE3-mediated sodium and hydrogen ion antiport (EC₅₀Na), which is determined by the formula EC₅₀P_u = (r)EC₅₀Na, in which r is from about 0.6 to about 1.5, preferably from about 0.7 to about 1.3 or from about 0.6, 0.65, 0.7, 0.75, 0.8 , 0.85, 0.9, 0.95, 1.0, 1.1, 1.2, 1.3, 1.4, or 1.5, including all ranges in between. In some embodiments, for example, when administered that achieves systemic availability (e.g., results in activity in the kidneys), some compounds may have an EC₅₀ in relation to the increase in the output of phosphate ions in the urine (EC₅₀P_u) and EU₅₀ regarding inhibition of NHE3-mediated sodium and hydrogen ion antiport (EC₅₀Na), which is determined by the formula EC₅₀P_u = (r)EC₅₀Na, in which r is from about 0.6 to about 1.5, preferably from about 0.7 to about 1.3 or about 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.1, 1.2, 1.3, 1.4, or 1.5, including all ranges in between. In particular embodiments, for example, when administered to a patient for whom there is a need for a phosphate reduction or cell-based test, some compounds may have EU₅₀ with respect to inhibition of phosphate ion transport (EC_50P) and EU₅₀ with respect to inhibition of NHE3-mediated sodium and hydrogen ion antiport (EC₅₀Na), which is determined by the formula EC₅₀P = (r)EC₅₀Na, in which r is from about 0.6 to about 1.5, preferably from about 0.7 to about 1.3 or about 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.1, 1.2, 1.3, 1.4, or 1.5, including all ranges in between.

In some embodiments, and in addition to its effects on Pi levels, administration of a dual potency compound (or at a dosage that provides dual potency) to a patient (eg, by enteral administration) increases the patient's daily faecal sodium and/or fluid output. In some cases, fecal sodium output is increased by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 200 %, 300%, 400%, 500%, 600%, 700%, 800%, 900%, 1000%, 1100%, 1200%, 1300%, 1400%, 1500%, 1600%, 1700%, 1800%, 1900% or 2000% or more relative to the raw state. In some cases, the liquid yield or water content of the faeces is increased by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 200%, 300%, 400%, 500%, 600%, 700%, 800%, 900%, 1000%, 1100%, 1200%, 1300%, 1400%, 1500%, 1600%, 1700% , 1800%, 1900%, or 2000% or more relative to the raw state.

B. Monoactive compounds

Some embodiments relate to NHE3-binding compounds that inhibit phosphate ion (Pi) transport and but do not substantially inhibit NHE3-mediated sodium and hydrogen ion antiport, for example, at a given dosage. These and related embodiments include, for example, non-persistent NHE3 ligands that are substantially active in inhibiting Pi transport but substantially inactive in the gastrointestinal tract and/or kidneys in inhibiting NHE3-mediated sodium and hydrogen ion antiport when administered. patient. In some embodiments, the non-persistent NHE3 ligands are substantially inactive in the colon (eg, when administered enterally) to inhibit NHE3-mediated sodium and hydrogen ion antiport.

In some aspects, the non-persistent NHE3 ligand is characterized by its maximal inhibitory activity against NHE3-mediated sodium and hydrogen ion antiport, for example, in a cell-based assay or other in vitro assay. In one example, a non-persistent NHE3 ligand has a maximum inhibition of NHE3-mediated sodium and hydrogen ion antiport of about or less than about 50%, 40%, 30%, 35%, 20%, 15%, 10%, or 5%, with the maximum inhibition characterized by the inhibitory activity of the compound in the in vitro NHE3-mediated sodium and hydrogen ion antiport inhibition assay and is relative to sodium-free conditions. In these and related embodiments, sodium-free conditions essentially represent zero activity for NHE3-mediated sodium and hydrogen ion antiportation, and can thus be used to establish a value for 100% or maximum inhibition.

In some aspects, non-persistent NHE3 ligands are characterized by their "non-persistence" in binding to NHE3 and inhibition of NHE3-mediated sodium and hydrogen ion antiport, i.e., their relative absence or reduction of "persistent inhibition" of NHE-mediated sodium and hydrogen ion antiport. In particular aspects, persistent inhibition is characterized by the time-dependent inhibitory activity of a compound in an in vitro NHE3-mediated sodium and hydrogen ion antiport inhibition assay, e.g. PNAS USA (1984) 81(23): 7436-7440 and Examples 1-2). Examples of constant and fast conditions are described above.

In some aspects, non-persistent NHE3 ligands are characterized by time-dependent inhibitory activity of the compound inin vitro test of inhibition of NHE3-mediated antiport of sodium and hydrogen ions, and pIC₅₀ connections in fast conditions (pIC_50promp) is greater than or substantially greater than pIC₅₀ connections under constant conditions (pIC_50pers). Essentially more includes, for example, cases where pIC_50promp more than pIC_50pers about or at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 200% or more. In private aspects pIC_50promp is about or at least about 7.0, including about or at least about 6.5, 6.55. 6.6, 6.65, 6.7. 6.75, 6.8, 6.85, 6.9, 6.95, 7.0, 7.05, 7.1, 7.15, 7.2, 7.25, 7.3, 7, 35, 7.4, 7.45, 7.5, 7.55, 7.6, 7.65. 7.7, 7.75, 7.8, 7.85, 7.9, 7.95, 8.0, 8.05, 8.1, 8.15, 8.2, 8.25, 8, 3, 8.35, 8.4, 8.45, 8.5, 8.55, 8.6, 8.65, 8.7, 8.75, 8.8, 8.85, 8.9, 8.95 or 9.0, and pIC_50pers is about or less than about 6.0, including about or less than about 6.4, 6.35, 6.3, 6.25, 6.2, 6.15, 6.1, 6.05, 6, 0, 5.95, 5.9, 5.85, 5.7, 5.75, 5.6, 5.65, 5.5, 5.45, 5.4, 5.35, 5.3, 5.25, 5.2, 5.15, 5.1, 5.05, 5.0, 4.95, 4.9, 4.85, 4.8, 4.75, 4.7, 4, 65, 4.6, 4.55, 4.5, 4.45, 4.4, 4.35, 4.3, 4.25, 4.2, 4.15, 4.1, 4.05, 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 or 3.0.

In some aspects, IC₅₀ volatile NHE3 ligand in fast conditions (IC_50promp) is essentially less than IC₅₀ connections under constant conditions (IC_50pers)_. Essentially less includes, for example, cases where IC_50promp is less than IC_50pers about or at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 200%, 300%, 400%, 500%, or 1000%. For example, in some aspects, IC_50promp is about or less than about 0.3, 0.2, 0.1, .009, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0 .01, 0.009, 0.008, 0.007, 0.006, 0.005, 0.004, 0.003, 0.002, or 0.001 µM, or ranges from about 0.001-0.3, 0.001-0.2, 0.001-0.1, 0.001-0.05, 0.001-0.01, 0.001-0.005 µM, or ranges from about 0.005-0.3, 0.005-0.2, 0.005-0.1, 0.005-0.05, 0.005-0.01, or ranges from about 0 .01-0.3, 0.01-0.2, 0.01-0.1, or 0.01-0.05 µM, or ranges from about 0.1-0.3 or 0.1-0, 2 µM, and IC_50pers about or greater than about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300 , 400, 500, 600, 700, 800, 900 or 1000 μM or more, or is from about 1-10, 1-20, 1-30, 1-40, 1-50, 1-100, 1-500, 1-1000 µM, or is from about 2-10, 2-20, 2-30, 2-40, 2-50, 2-100, 2-500, 2-1000 µM, or is from about 5-10, 5-20, 5-30, 5-40, 5-50, 5-100, 5-500, 5-1000 µM, or about 10-20, 10-30, 10-40, 10-50, 10 -100, 10-500, 10-1000 µM, or ranges from about 20-30, 20-40, 20-50, 20-100, 20-500, 20-1000 µM, or ranges from about 50-100, 50 -500, 50-1000 µM, or ranges from about 100-500 or 100-1000 µM.

In some aspects, non-persistent NHE3 ligands are characterized by their relative activity in inhibiting phosphate transport and inhibiting NHE3-mediated sodium and hydrogen ion antiport. For example, when administered enterally to a patient for whom there is a need for a decrease in phosphate, some compounds may have EU₅₀ to increase the excretion of phosphate ions in the feces (EC₅₀P_f) and EU₅₀ with respect to inhibition of NHE3-mediated sodium and hydrogen ion antiport (EC₅₀Na), which is determined by the formula EC₅₀P_f = (r)EC₅₀Na, in which r is from about 0.1 to about 0.5, or about 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4 , 0.45, 0.5, or 0.55, including all ranges in between. In some embodiments, for example, when administered enterally to a patient for whom there is a need for a decrease in phosphate, some compounds may have EU₅₀ to reduce the output of phosphate ions in the urine (EC₅₀P_u) and EU₅₀ with respect to inhibition of NHE3-mediated sodium and hydrogen ion antiport (EC₅₀Na), which is determined by the formula EC₅₀P_u = (r)EC₅₀Na, in which r is from about 0.1 to about 0.5, or about 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4 , 0.45, 0.5, or 0.55, including all ranges in between. In particular embodiments, for example, when administered enterally to a patient for whom there is a need for a reduction in phosphate levels, or in a cell-based test, some compounds may have EU₅₀ with respect to inhibition of phosphate ion transport (EC_50P) and EU₅₀ with respect to inhibition of NHE3-mediated sodium and hydrogen ion antiport (EC₅₀Na), which is determined by the formula EC₅₀P = (r)EC₅₀Na, in which r is from about 0.05 or 0.1 to about 0.5 or about 0.55, or about 0.05, 0.1, 0.15, 0.2, 0.25, 0, 3, 0.35, 0.4, 0.45, 0.5, or 0.55, including all ranges in between. In some embodiments, for example, when administered that achieves systemic availability (e.g., results in significant activity in the kidneys), some of the non-persistent NHE3 ligand compounds may have EU₅₀ in relation to the increase in the output of phosphate ions in the urine (EC₅₀P_u) and EU₅₀ with respect to inhibition of NHE3-mediated sodium and hydrogen ion antiport (EC₅₀Na), which is determined by the formula EC₅₀P_u = (r)EC₅₀Na, in which r is from about 0.1 to about 0.5, or about 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4 , 0.45, 0.5, or 0.55, including all ranges in between.

In some embodiments, administration of a volatile NHE3 ligand to a patient (e.g., by enteral administration) increases the phosphate/sodium ratio in faecal excretion by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 200% or more relative to the raw state. In some embodiments, administration to a patient (eg, by enteral administration) increases daily fecal phosphate excretion without substantially modulating stool shape or fecal water content. For example, in these and related embodiments, the shape of the fecal stool can be about or within about 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15 % or 20% fecal stool form relative to the untreated state. In some aspects, the fecal form according to the Bristol Stool Form Scale (Types 1, 2, 3, 4, 5, 6 and 7; Type 1 being hard and Type 7 being watery) may be the same or within about 1-2 units relative to the raw state (see, for example, Rao et al., Neurogastroenterol Motil. 23:8-23, 2011; and Lewis and Heaton, Scand. J. Gastroenterol. 32:920-4, 1997). In some aspects, the fecal form according to the Bristol Stool Form Scale corresponds to Type 3 or Type 4. In some embodiments, administration to a rodent (e.g., rat, mouse) increases the ratio of sodium in the small intestine (Na_SI)/caecum (Na_c) by at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 200% or more relative to the untreated state.

II. Essentially systemically non-bioavailable compounds

A. Physical and performance properties of compounds localized in the GI tract

Some of the compounds described herein are designed to be substantially active or localized in the gastrointestinal lumen of animals or humans. The term "gastrointestinal lumen" is used here interchangeably with the term "lumen" and refers to a space or cavity within the gastrointestinal tract (GI tract, which may also be referred to as the intestine) delimited by the apical membrane of a patient's gastrointestinal epithelial cells. In some embodiments, the compounds are not absorbed through the epithelial cell layer of the GI tract (also known as the gastrointestinal epithelium). "Gastrointestinal mucosa" refers to the layer(s) of cells that separate the gastrointestinal lumen from the rest of the body and includes the lining of the stomach and intestines, such as the lining of the small intestine. "Gastrointestinal epithelial cell" or "intestinal epithelial cell" as used herein refers to any epithelial cell on the mucosal surface of the gastrointestinal tract facing the lumen of the gastrointestinal tract, including, for example, gastric epithelial cell, intestinal epithelial cell, colonic and colonic epithelial cell intestines, etc.

"Substantially systemically non-bioavailable" and/or "substantially impermeable" as used herein (as well as variations of the term) generally refer to situations in which a statistically significant amount, and in some embodiments substantially all of the compound, remains in the gastrointestinal tract. intestinal lumen. For example, in accordance with one or more embodiments of the present disclosure, preferably at least about 60%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 96%, about 97%, about 98%, about 99%, or even about 99.5% of the compound remains in the gastrointestinal lumen. In such cases, localization in the gastrointestinal lumen refers to the reduction of the net movement of the compound through the epithelial cell layer of the gastrointestinal tract, for example, through both transcellular and paracellular transport, as well as active and/or passive transport. The compound in such embodiments encounters obstacles to clean penetration through the gastrointestinal epithelial cell layer in transcellular transport, for example across the apical membrane of the small intestinal epithelial cell. The compound in these embodiments also encounters obstacles to clean penetration through "tight junctions" in paracellular transport between gastrointestinal epithelial cells lining the lumen.

In this regard, it should be noted that, in one particular embodiment, the compound is essentially not absorbed at all by the GI tract or gastrointestinal lumen. Within the scope of the invention, the terms "substantially impermeable" or "substantially systemically non-bioavailable" include embodiments in which no detectable amount of absorption or permeation or systemic exposure of the compound is detected using means commonly known in the art.

In this regard, it should be further noted, however, that in alternative embodiments, "substantially impermeable" or "substantially systemically non-bioavailable" allows for or allows for some limited absorption in the GI tract, and more specifically the intestinal epithelium (e.g., some detectable amount of absorption, such as, for example, at least about 0.1%, 0.5%, 1%, or more, and less than about 30%, 20%, 10%, 5%, etc., and the absorption range is, for example , about 1% to 30%, or 5% to 20%, etc.); in other words, "substantially impermeable" or "substantially systemically non-bioavailable" may refer to compounds that exhibit some detectable permeability to the epithelial layer of cells in the GI tract of less than about 20% of the administered compound (e.g., less than about 15%, about 10 % or even about 5%, 4%, 3% or 2%, and for example, more than about 0.5% or 1%), but then they are excreted by the liver (i.e., hepatic extraction) and/or kidneys (i.e., renal excretion).

In this regard, it should also be noted that in some embodiments, due to the substantially impermeable and/or substantially systemic non-bioavailability of the compounds of the present invention, greater than about 50%, 60%, 70%, 80%, 90%, or 95% a compound of the invention can be recovered from the end feces over a period of, for example, 24, 36, 48, 60, 72, 84, or 96 hours after administration to a patient. In this regard, it should be understood that the recovered compound may include the sum of the parent compound and its metabolites derived from the parent compound, for example, via hydrolysis, conjugation, reduction, oxidation, N-alkylation, glucuronidation, acetylation, methylation, sulfation, phosphorylation, or any another modification that adds atoms to or removes atoms from the parent compound, wherein the metabolites are produced by the action of any enzyme or exposure to any physiological environment, including pH, temperature, pressure, or interactions with food in the digestive environment.

The measurement of fecal recovery of the compound and metabolites can be carried out using standard methodology. For example, the compound may be administered orally at a suitable dose (eg, 10 mg/kg) and feces are then collected at predetermined times after administration (eg, 24 hours, 36 hours, 48 hours, 60 hours, 72 hours, 96 hours). The parent compound and metabolites can be extracted with an organic solvent and analyzed quantitatively using mass spectrometry. Analysis of the mass balance of the parent compound and metabolites (including parent = M, metabolite 1 [M+16] and metabolite 2 [M+32]) can be used to determine the percentage of recovery in the feces.

(i) Permeability

In this regard, it should be noted that, in various embodiments, the ability of a compound to be substantially systemically non-bioavailable is based on the charge, size, and/or other physicochemical parameters of the compound (e.g., polar surface area, number of hydrogen bond donors and/or acceptors, the number of freely rotating bonds, etc.). More specifically, it should be noted that the absorption pattern of a compound can be selected using the principles of pharmacokinetics, for example, using Lipinski's rule, also known as the "rule of five". Although not a rule, but rather a set of guidelines, Lipinski's rule shows that drugs that are small molecules with (i) molecular weight, (ii) number of hydrogen bond donors, (iii) number of hydrogen bond acceptors, and/ or (iv) a water/octanol partition coefficient (Moriguchi Log P) greater than a certain threshold, does not show significant systemic concentration at all (i.e., is not absorbed to any significant extent at all). (See, for example, Lipinski et al, Advanced Drug Delivery Reviews, 46:3-26, 2001, incorporated herein by reference). Accordingly, substantially systemically non-bioavailable compounds can be designed to have molecular structures that exceed one or more Lipinski thresholds (See also Lipinski et al., Experimental and Computational Approaches to Estimate Solubility and Permeability in Drug Discovery and Development Settings, Adv. Drug Delivery Reviews, 46:3-26 (2001), and Lipinski, Drug-like Properties and the Causes of Poor Solubility and Poor Permeability, J. Pharm. & Toxicol. Methods, 44:235-249 (2000), included in the present description by reference).

In some embodiments, for example, a substantially impermeable or substantially systemically non-bioavailable compound of the present disclosure may be prepared to exhibit one or more of the following characteristics: (i) a molecular weight greater than about 500 Da, about 600 Da, about 700 Yes, approx. 800 Da, approx. 900 Da, approx. about 4000 Da, about 5000 Da, about 7500 Da, about 10000 Da or more (in the non-salt form of the compound); (ii) the total amount of NH and/or OH and/or other potential hydrogen bond donors is greater than about 5, about 6, about 7, about 8, about 9, about 10, about 11, about 12, about 13, about 14, about 15, about 20 or more; (iii) the total number of O atoms and/or N atoms and/or other potential hydrogen bond acceptors is greater than about 5, about 6, about 7, about 8, about 9, about 10, about 11, about 12, about 13, about 14, about 15, about 20 or more; (iv) the Moriguchi partition coefficient is greater than about ¹⁰⁵ (i.e., Log P is greater than about 5, about 6, about 7, about 8, about 9, about 10, etc.), or alternatively less than about 10 ( that is, Log P is less than 1 or even 0); and/or (v) the total number of rotatable bonds is greater than about 5, about 10, or about 15, or more. In some embodiments, the connection has a Log P that is not equal to 14 or less than about 14, for example, a Log P that is in the range of about 6-7, 6-8, 6-9, 6-10, 6-11 , 6-12, 6-13, 7-8, 7-9, 7-10, 7-11, 7-12, 7-13, 8-9, 8-10, 8-11, 8-12, 8 -13, 9-10, 9-11, 9-12, 9-13, 10-11, 10-12, 10-13, 11-12, 11-13 or 12-13.

In addition to the parameters noted above, the polar surface molecular area (i.e., "PSA"), which can be characterized as the surface belonging to polar atoms, is a parameter that has also been shown to correlate well with passive transport across membranes and therefore allows you to make a prediction of the transport properties of drugs. It has been successfully used to predict intestinal absorption and permeation through a monolayer of Caco2 cells. For an example of details of determining penetration through a monolayer of Caco2 cells, see for example the description of the Caco2 Model in US Pat. testing compounds according to the present invention. PSA is expressed in Å ² (square angstrom) and is calculated from the three-dimensional representation of the molecule. A fast calculation method is also available (see, for example, Ertl et al, Journal of Medicinal Chemistry, 2000, 43, 3714-3717, the entire contents of which are incorporated herein by reference for all relevant and consistent purposes) using a personal computer and commercially. available chemical drawing tools such as ChemDraw. The term "topological PSA" (tPSA) has been coined for this fast calculation method. tPSA correlates well with human absorption data of conventional drugs (see Table 1 from Ertl et al, J. Med. Chem., 2000, 43:3714-3717):

Table 1 Name %FA ^{a TPSAb} metoprolol 102 50.7 Nordiazepam 99 41.5 Diazepam 97 32.7 Oxprenolol 97 50.7 Phenazone 97 26.9 Oxazepam 97 61.7 Alprenolol 96 41.9 Parktolol 95 70.6 Pindolol 92 57.3 Ciprofloxcin 69 74.6 Metolazone 64 92.5 Tranexamic acid 55 63.3 Atenolol 54 84.6 Sulpiride 36 101.7 Mannitol 26 121.4 Foscarnet 17 94.8 Sulfasalazine 12 141.3 Olsalazin 2.3 139.8 Lactulose 0.6 197.4 Raffinose 0.3 268.7

Accordingly, in some embodiments, compounds of the present disclosure may be prepared so as to exhibit a tPSA value greater than about 100 Å ² , about 116 Å ² , about 120 Å ² , about 130 Å ² , or about 140 Å ² , and in some cases approximately 150 Å ² , approximately 160 Å ² , approximately 170 Å ² , approximately 180 Å ² , approximately 190 Å ² , approximately 200 Å ² , approximately 225 Å ² , approximately 250 Å ² , approximately 270 Å ² , approximately 300 Å ² , about 350 Å ² , about 400 Å ² , about 450 Å ² , about 500 Å ² , about 750 Å ² , or even about 1000 Å ² , or in the range of about 100-120 Å ² , 100-130 Å ² 100-140 Å ² 100-150 Å ² 100-160 Å ² 100-170 Å ² 100-170 Å ² 100-190 Å ² 100-200 Å ² 100-225 Å ² 100 -250 Å ² , 100-300 Å ² , 100-400 Å ² , 100-500 Å ² , 100-750 Å ² , 100-1000 Å ² , 116-120 Å ² , 116-130 Å ² , 116-140 Å ² , 116-150 Å ² , 116-160 Å ² , 116-170 Å ² , 116-170 Å ² , 116-190 Å ² , 116-200 Å ² 116-225 Å ² 116-250 Å ² 116-300 Å ² 116-400 Å ² 116-500 Å ² 116-750 Å ² 116-1000 Å ² 120-130 Å ² -140 Å ² , 120-150 Å ² , 120-160 Å ² , 120-170 Å ² , 120-170 Å ² , 120-190 Å ² , 120-200 Å ² , 120-225 Å ² , 120-250 Å ² , 120-300 Å ² , 120-400 Å ² , 120-500 Å ² , 120-750 Å ² , 120-1000 Å ² , 130-140 Å ² , 130-150 Å ² , 130-160 Å ² 130-170 Å ² 130-170 Å ² 130-190 Å ² 130-200 Å ² 130-225 Å ² 130-250 Å ² 130-300 Å ² 130-400 Å ² 130 -500 Å ² , 130-750 Å ² , 130-1000 Å ² , 140-150 Å ² , 140-160 Å ² , 140-170 Å ² , 140-170 Å ² , 140-190 Å ² , 140-200 Å ² , 140-225 Å ² , 140-250 Å ² , 140-300 Å ² , 140-400 Å ² , 140-500 Å ² , 140-750 Å ² , 140-1000 Å ² , 150-160 Å ² , 150-170 Å ² , 150-170 Å ² , 150-190 Å ² , 150-200 Å ² , 150-225 Å ² , or 150-250 Å ² , 150-300 Å ² , 150-400 Å ² , 150-500 Å ² , 150-750 Å ² , 150-1000 Å ² , 200-250 Å ² , 200- 300 Å ² , 200-400 Å ² , 200-500 Å ² , 200-750 Å ² , 200-1000 Å ² , 250-250 Å ² , 250-300 Å ² , 250-400 Å ² , 20-500 Å ² , 250-750 Å ² , or 250-1000 Å ² , such that the compounds are substantially impermeable (eg, cell-impermeable) or substantially systemically non-bioavailable (as defined elsewhere herein).

Because there are exceptions to the Lipinski "rule" or tPSA model, the permeability properties of the compounds of the present disclosure can be experimentally screened. The permeability coefficient can be determined by methods known to those skilled in the art, including, for example, the Caco-2 cell permeability test and/or using an artificial membrane as a gastrointestinal epithelial cell model. A synthetic membrane impregnated with, for example, lecithin and/or dodecane to mimic the net permeability characteristics of the gastrointestinal mucosa can be used as a model of the gastrointestinal mucosa. The membrane can be used to separate the compartment containing the compound of the present disclosure from the compartment in which penetration is being tested. In addition, parallel artificial membrane permeability tests (PAMPA) can be performed. Such in vitro measurements can show actual in vivo permeability (see Wohnsland et al, J. Med. Chem. 44:923-930, 2001; Schmidt et al, Millipore Corp. Application Note, 2002, n AN 1725EN00 and n AN 1728EN00 included in the present description by reference).

Accordingly, in some embodiments, the compounds used in the methods of the present disclosure may have a permeability coefficient P_app, less than about 100×10^-6 cm/s, or less than about 10×10^-6 cm/s or less than about 1×10^-6 cm/s, or less than about 0.1×10^-6 cm/s, when measured using means known in the art (such as, for example, the permeability experiment described in Wohnsland et al, 2001, supra).

As previously noted, in accordance with the present disclosure, the compounds can be modified in such a way as to impede their net absorption through the intestinal epithelial cell layer, rendering them essentially systemically non-bioavailable. In some particular embodiments, the compounds of the present disclosure include a compound that is bonded to, combined with, or otherwise attached to a non-absorbable group, which may be an oligomeric group, a polymeric group, a hydrophobic group, a hydrophilic group, and/or a charged group, which makes the entire compound substantially impermeable or essentially systemically non-bioavailable. In some preferred embodiments, the compound is attached to a multimer or polymer moiety or group such that the final molecule is substantially impermeable or substantially systemically non-bioavailable. The multimeric or polymeric moiety or group may have a molecular weight greater than about 500 Daltons (Da), about 1000 Da, about 2500 Da, about 5000 Da, about 10000 Da or more, and in particular may have a molecular weight in the range of about 1000 Daltons (Da) up to about 500,000 Da, preferably in the range of about 5,000 to about 200,000 Da, and more preferably may have a molecular weight that is high enough to substantially impede any net absorption of the compound through the intestinal epithelial cell layer. In these or other particular embodiments, the compound is modified to substantially hinder its net absorption through the intestinal epithelial cell layer.

(ii) C _max and IC ₅₀ or EU ₅₀

In some embodiments, the substantially systemically non-bioavailable compounds detailed herein when administered (e.g., enterally) alone or in combination with one or more additional pharmaceutically active compounds or agents to a patient exhibit a maximum concentration detectable in serum, defined as C_max, which is approximately the same or less than the inhibitory transport or uptake of phosphate ions (Pi) concentration IC₅₀ connections. In some embodiments, for example, about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% less than IC₅₀ regarding inhibition of Pi transport or uptake. In some embodiments, C_max is approximately 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9X (0.9 times) IC₅₀ regarding inhibition of Pi transport or uptake.

In some embodiments, one or more of the substantially systemically non-bioavailable compounds detailed herein, when administered (eg, enterally) to a patient, may be related to C_max:IC₅₀ (in relation to the inhibition of the transport or capture of Pi), and C_max and IC₅₀ expressed in the same units, about or less than about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0, 1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0, or a range between approximately 0.01-1.0, 0.01-0.9, 0.01-0.8, 0.01-0.7, 0.01-0.6, 0.01-0.5, 0.01-0.4, 0, 01-0.3, 0.01-0.2, or 0.01-0.1, or range between approximately 0.1-1.0, 0.1-0.9, 0.1-0.8 , 0.1-0.7, 0.1-0.6, 0.1-0.5, 0.1-0.4, 0.1-0.3 or 0.1-0.2.

In some embodiments, the substantially systemically non-bioavailable compounds detailed herein, when administered (e.g., enterally) alone or in combination with one or more additional pharmaceutically active compounds or agents to a patient, exhibit a maximum concentration detectable in serum, defined as C_max, which is approximately the same or less than EU₅₀ compounds in terms of increasing fecal phosphate excretion, wherein fecal excretion is increased by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90 % or 100%. In some embodiments, for example, C_max about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% less than EU₅₀ in relation to increased excretion of phosphate in the feces. In some embodiments, C_max is approximately 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9X (0.9 times) of EU₅₀ in relation to increased excretion of phosphate in the feces.

In some embodiments, one or more of the substantially systemically non-bioavailable compounds detailed herein when administered (e.g., enterally), alone or in combination with one or more additional pharmaceutically active compounds or agents to a patient, or as measured in an animal model or cell-based test, may have EC₅₀ in relation to an increase in fecal phosphate excretion of about or less than about 10 μM, 9 μM, 8 μM, 7 μM, 7.5 μM, 6 μM, 5 μM, 4 μM, 3 μM, 2.5 μM, 2 μM, 1 μM, 0.5 μM, 0.1 μM, 0.05 μM, or 0.01 μM or less, and IC₅₀ is, for example, in the range from about 0.01 µM to about 10 µM, or from about 0.01 µM to about 7.5 µM, or from about 0.01 µM to about 5 µM, or from about 0.01 µM to about 2.5 µM, or from about 0.01 µM to about 1.0, or from about 0.1 µM to about 10 µM, or from about 0.1 µM to about 7.5 µM, or from about 0 .1 µM to about 5 µM, or from about 0.1 µM to about 2.5 µM, or from about 0.1 µM to about 1.0 µM, or from about 0.5 µM to about 10 µM, or from about 0.5 µM to about 7.5 µM, or about 0.5 µM to about 5 µM, or about 0.5 µM to about 2.5 µM, or about 0.5 µM to about 1.0 µM.

In particular embodiments, the substantially systemically non-bioavailable compounds detailed herein, when administered (e.g., enterally) alone or in combination with one or more additional pharmaceutically active compounds or agents to a patient, exhibit a maximum concentration detectable in serum, defined as C_max, which is approximately the same or less than EU₅₀ compounds in terms of reducing urinary phosphate excretion, wherein urinary excretion is reduced by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90 % or 100%. In some embodiments, for example, C_max about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% less than EU₅₀ in relation to a decrease in the excretion of phosphate in the urine. In some embodiments, C_max is approximately 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9X (0.9 times) from EU₅₀ in relation to a decrease in the excretion of phosphate in the urine.

In some embodiments, one or more of the substantially systemically non-bioavailable compounds detailed herein when administered (e.g., enterally), alone or in combination with one or more additional pharmaceutically active compounds or agents to a patient, or when measured in an animal model or in cell-based test, may have EC₅₀ in relation to reduction in urinary phosphate excretion of about or less than about 10 μM, 9 μM, 8 μM, 7 μM, 7.5 μM, 6 μM, 5 μM, 4 μM, 3 μM, 2.5 μM, 2 μM, 1 μM, 0.5 μM, 0.1 μM, 0.05 μM or 0.01 μM, or less, and IC₅₀ is, for example, in the range from about 0.01 µM to about 10 µM, or from about 0.01 µM to about 7.5 µM, or from about 0.01 µM to about 5 µM, or from about 0.01 µM to about 2.5 µM, or from about 0.01 µM to about 1.0, or from about 0.1 µM to about 10 µM, or from about 0.1 µM to about 7.5 µM, or from about 0 .1 µM to about 5 µM, or from about 0.1 µM to about 2.5 µM, or from about 0.1 µM to about 1.0 µM, or from about 0.5 µM to about 10 µM, or from about 0.5 µM to about 7.5 µM, or about 0.5 µM to about 5 µM, or about 0.5 µM to about 2.5 µM, or about 0.5 µM to about 1.0 µM.

In some embodiments, one or more of the substantially systemically non-bioavailable compounds detailed herein, when administered (eg, enterally) to a patient, may be related to C_max:EC₅₀ (for example, in relation to an increase in phosphate excretion with feces, in relation to a decrease in urinary phosphate excretion), and C_max and EU₅₀ expressed in the same units, about or less than about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0, 1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0, or in the range of about 0.01-1.0, 0.01-0.9, 0.01-0.8, 0.01-0.7, 0.01-0.6, 0.01-0.5, 0.01-0.4, 0, 01-0.3, 0.01-0.2, or 0.01-0.1, or in the range of approximately 0.1-1.0, 0.1-0.9, 0.1-0.8, 0.1-0.7, 0.1-0.6, 0.1-0.5, 0.1-0.4, 0.1-0.3 or 0.1-0.2.

Additionally, or alternatively, one or more of the substantially systemically non-bioavailable compounds detailed herein, when administered (eg, enterally) alone or in combination with one or more additional pharmaceutically active compounds or agents to a patient, may have a C _max of about or less than about 10 ng/ml, about 7.5 ng/ml, about 5 ng/ml, about 2.5 ng/ml, about 1 ng/ml, or about 0.5 ng/ml, with C _max being, for example, range from about 1 ng/ml to about 10 ng/ml, or from about 2.5 ng/ml to about 7.5 ng/ml.

B. Structure Examples

Generally speaking, the present disclosure encompasses essentially any small molecule, which may be monovalent or polyvalent, that binds to and/or modulates NHE3 and has activity as a phosphate transport inhibitor, including small molecules that are substantially impermeable or substantially systemically non-bioavailable in gastrointestinal tract, including known NHE binding compounds that can be modified or functionalized in accordance with the present disclosure to change the physico-chemical properties in such a way as to make the complete connection essentially active in the GI tract.

Accordingly, the compounds of the present disclosure may generally be represented by Formula (I):

,

,

in which: (i) NHE denotes an NHE-binding small molecule, and (ii) Z denotes a group having at least one site for attachment to an NHE-binding small molecule, and the resulting NHE-Z molecule has generally physicochemical properties which render it substantially impermeable or substantially systemically non-bioavailable. An NHE-binding small molecule generally includes a heteroatom-containing group and a cyclic or heterocyclic backbone or carrier group directly or indirectly linked to it. In particular, studies of the structures of small molecules currently known to be NHE-binding or inhibitory suggest, as further illustrated here below, that most of them include a cyclic or heterocyclic carrier group or backbone linked directly or indirectly (through, for example, an acyl group or a hydrocarbyl or heterohydrocarbyl group such as an alkyl, alkenyl, heteroalkyl, or heteroalkenyl group) with a heteroatom-containing group that can act as a sodium atom or sodium ion mimetic, which is typically selected from a substituted guanidinyl group and a substituted heterocyclic groups (eg nitrogen-containing heterocyclic group). If desired, the heteroatom-containing group may be fused to the backbone or carrier group to form a fused bicyclic structure and/or it may be capable of forming a positive charge at physiological pH.

In this regard, it should be noted that although a heteroatom-containing group that can act as a sodium atom or ion mimetic can, if necessary, form a positive charge, this should not be understood or interpreted as requiring that the entire compound have a net positive charge or only a single positively charged group. Rather, in various embodiments, the compound may not have any charged groups, or it may have multiple charged groups (which may have positive charges, negative charges, or a combination of these, the compound may be a zwitterion, for example). Additionally, it should be understood that a complete connection may have a net neutral charge, a net positive charge (eg +1, +2, +3, etc.), or a net negative charge (eg -1, -2, -3 etc.).

The Z group may be linked to essentially any position on or within the small NHE molecule, and in particular may be: (i) linked to a backbone or carrier group, (ii) linked to a position on or within a heteroatom-containing group. composition, and/or (iii) is linked to a position on or within an intermediate group that links the scaffold to a heteroatom-containing group, provided that the installation of the Z group does not significantly adversely affect NHE-binding activity. In one particular embodiment, Z may be in the form of an oligomer, dendrimer, or polymer associated with a small NHE molecule (e.g., associated, for example, with a scaffold or spacer group), or alternatively, Z may be in the form of a linker that connects a plurality of small molecules NHE, and therefore acts to increase: (i) the total molecular weight and/or polar surface area of the NHE-Z molecule; and/or (ii) the number of free-rotating bonds in the NHE-Z molecule; and/or (iii) the number of hydrogen bond donors and/or acceptors in the NHE-Z molecule; and/or (iv) a Log P value of the NHE-Z molecule up to a value of at least about 5 (or alternatively less than 1, or even about 0), all as set forth herein; such that the complete NHE binding compound (ie, the NHE-Z compound) is substantially impermeable or substantially systemically non-bioavailable.

The present disclosure is directed in more detail to such a substantially impermeable or substantially systemically non-bioavailable NHE binding compound, or pharmaceutical salt thereof, wherein the compound has the structure of Formula (II):

Substantially impermeable and/or essentially systemically non-bioavailable NHE inhibitory compound

in which: (i) Z, as defined above, is a group associated with or included in an NHE-binding small molecule, such that the resulting NHE-Z molecule has in general physico-chemical properties that make it essentially impermeable or essentially systemically non-bioavailable; (ii) B is a heteroatom-containing group of an NHE-binding small molecule, and in one particular embodiment is selected from a substituted guanidinyl group and a substituted heterocyclic group, which may optionally be fused to a Carcass group to form a fused bicyclic structure; (iii) The backbone is a cyclic or heterocyclic group to which is directly or indirectly linked a heteroatom containing a group (eg, a substituted guanidinyl group or a substituted heterocyclic group) B and which may be substituted with one or more additional hydrocarbyl or heterohydrocarbyl groups; (iv) X is a bond or an intermediate group selected from the group consisting of substituted or unsubstituted hydrocarbyl or heterohydrocarbyl groups, and in particular substituted or unsubstituted C₁-C₇ hydrocarbyl or heterohydrocarbyl (for example, C₁-C₇ alkyl, alkenyl, heteroalkyl or heteroalkenyl), and substituted or unsubstituted, saturated or unsaturated, cyclic or heterocyclic groups (for example, C_four-C₇ cyclic or heterocyclic groups) that links B and Framework; and (v) D and E are integers that are each independently 1, 2, or greater.

In one or more particular embodiments, as further illustrated herein below, B may be selected from a guanidinyl group or a group that is a bioisostere of guanidinyl selected from the group consisting of substituted cyclobutenedione, substituted imidazole, substituted thiazole, substituted oxadiazole, substituted pyrazole, or substituted amine. More specifically, B can be selected from guanidinyl, acylguanidinyl, sulfonylguanidinyl, or a guanidine bioisostere such as cyclobutenedione, a substituted or unsubstituted 5- or 6-membered heterocycle such as a substituted or unsubstituted imidazole, aminoimidazole, alkylimidazole, thiazole, oxadiazole, pyrazole, alkylthioimidazole , or other functional group that can optionally become positively charged or function as a sodium mimetic, including amines (eg, tertiary amines), alkylamines, and the like, at physiological pH. In one particularly preferred embodiment, B is a substituted guanidinyl group or a substituted heterocyclic group which can optionally become positively charged at physiological pH and function as a sodium mimetic. In one embodiment, a compound of the present disclosure (or more specifically a pharmaceutically acceptable HC1 salt thereof as illustrated) may have the structure of Formula (III):

wherein Z may optionally be attached to any of a plurality of sites on the NHE-binding small molecule, and wherein the substituents R₁, R₂ and R₃ on aromatic rings, as detailed elsewhere in the specification and/or in US Pat. No. 6,399,824, the entire contents of which are incorporated herein by reference for all relevant and related purposes.

In this regard, it should be noted, however, that the substantially impermeable or substantially systemically non-bioavailable NHE binding compounds of the present disclosure may have a structure other than that illustrated above without departing from the scope of the present disclosure. For example, in various alternative embodiments, one or both of the terminal nitrogen atoms in the guanidine group may be substituted with one or more substituents, and/or a modifying or functionalizing Z group may be attached to the NHE-linking compound via (i) Framework, (ii ) a spacer X or (iii) a heteroatom-containing group B, as further illustrated generally in the structures shown below:

In this regard, it should be further noted that, within the scope of the invention, "bioisostere" generally refers to a group with similar physical and chemical properties to the guanidine group, which in turn imparts biological properties to this group, again similar to the guanidine group, in this case (See, for example, Ahmad, S. et al., Aminoimidazoles as Bioisosteres of Acylguanidines: Novel, Potent, Selective and Orally Bioavailable Inhibitors of the Sodium Hydrogen Exchanger Isoform-1, Boorganic & Med. Chem. Lett., pp. 177 -180 (2004), the entire contents of which are incorporated herein by reference for all relevant and related purposes).

As detailed below, known NHE-binding small molecules or chemotypes that may serve as suitable starting materials (for modification or functionalization to render small molecules substantially impermeable or substantially systemically non-bioavailable, and/or used in pharmaceutical formulations) may generally organize themselves into many subpopulations, such as, for example:

where: the terminal ring (or, in the case of non-acylguanidines, "R'') is a skeleton or carrier group; the guanidine group (or substituted heterocycle, and more particularly the piperidine ring, in the case of non-guanidine inhibitors) is B; and X is an acyl group or an -A-B-acyl- group (or a bond in the case of non-acyl guanidines and non-guanidine inhibitors.) (See, for example, Lang, H. J., "Chemistry of NHE Inhibitors" in The Sodium-Hydrogen Exchanger, Harmazyn, M., Avkiran, M. and Fliegel, L., Eds., Kluwer Academic Publishers 2003. See also B. Masereel et al., An Overview of Inhibitors of Na+ / H+ Exchanger, European J. of Med. Chem., 38, pp. 547- 554 (2003), the entire contents of which are incorporated herein by reference for all relevant and related purposes.) Without wishing to be bound by any particular theory, it has been suggested that a guanidine group or an acylguanidine group, or a charged guanidine or acylguanidine group (or, in the case of non-guanidine inhibitors, heterocy kl or other functional group that can replicate the intermolecular interactions of the guanidinyl functional group, including, but not limited to, the protonated nitrogen atom in the piperidine ring) at physiological pH can act as a sodium ion mimetic at the binding site of the exchanger or antiporter (See, for example, Vigne et al., J. Biol. Chem. 1982, 257, 9394).

Although a heteroatom-containing group may be capable of forming a positive charge, this should not be understood or interpreted as requiring that the entire compound have a net positive charge, or only a single positively charged group, or even that the heteroatom-containing group be capable of forming a positive charge in all cases. Rather, in various alternative embodiments, the compound may not have any charged groups, or it may have multiple charged groups (which may have positive charges, negative charges, or a combination of these). Additionally, it should be understood that a complete connection may have a net neutral charge, a net positive charge, or a net negative charge.

In this regard, it should be noted that the US patents and published US patent applications cited above or elsewhere in the description are hereby incorporated by reference in their entirety for all relevant and related purposes.

In addition to the structures illustrated above and elsewhere in the description, it should be noted that bioisosteric substitutions for guanidine or acylguanidine may also be used. Potentially viable bioisostere "guanidine substitutions" identified to date have a five- or six-membered heterocyclic ring with donor/acceptor structures and pKa similar to those of guanidine or acylguanidine (see, for example, Ahmad, S. et al., Aminoimidazoles as Bioisosteres of Acylguanidines: Novel, Potent, Selective and Orally Bioavailable Inhibitors of the Sodium Hydrogen Exchanger Isoform-1, Boorganic & Med. Chem. Lett., pp. 177-180 (2004), the entire contents of which are incorporated herein by reference for all relevant and related purposes) and include those illustrated below:

The above bioisostere variants (i.e., the group of structures above) correspond to the "B" in the structure of Formula (II), and the broken bond in them is attached to the "X" (for example, an acyl group, or alternatively a bond linking a bioisostere to a backbone) , with links to Z in Formula (III) not shown here.

It should be noted that, in many of the structures illustrated here, all of the various bonding structures or relationships will not be shown in every instance. For example, in one or more of the structures illustrated above, linking structures or bonds between the NHE-binding small molecule and the modifying or functionalizing group Z are not always shown. However, this should not be considered as a limitation. Rather, it should be understood that the NHE-binding small molecule is bound or attached in some way (e.g., by a bond or some sort of linker) to Z such that the resulting NHE-Z molecule is suitable for use (i.e., substantially impermeable or substantially systemically non-bioavailable in the GI tract). Alternatively, Z may be included in the NHE-binding small molecule, for example, as an insert between the guanidine group and the backbone.

It should also be noted that a variety of structures are provided herein for substantially impermeable or substantially systemically non-bioavailable NHE-binding compounds, and/or for NHE-linked small molecules suitable for modification or functionalization in accordance with the present disclosure to render them substantially impermeable. or essentially systemically non-bioavailable. Due to the large number of structures, different identifiers (eg, identifiers for an atom in a chain or ring, identifiers for substituents on a ring or chain, etc.) may be used more than once. An identifier in one structure need not therefore have the same value in another structure, unless specifically stated (e.g. "R ₁ " in one structure may or may not be the same as "R ₁ " in another structure) . Additionally, it should be noted that, in one or more of the structures further illustrated herein below, certain details of the structures, including one or more identifiers, may be given in the cited reference, the contents of which are specifically incorporated herein by reference for all relevant and related purposes.

C. Examples of small molecule variants

The substantially impermeable or substantially systemically non-bioavailable NHE3 binding compounds of the present disclosure can generally be derived from or derived from essentially any small molecule having the ability to bind to NHE3 and/or modulate NHE3, including small molecules that have already been reported or that have been identified as binding to NHE3 and/or modulating NHE3 activity, but not being impermeable (ie, not being essentially impermeable). In one particularly preferred embodiment, the compounds used in the various methods of the present disclosure are derived from or derived from small molecules that bind to the NHE3, -2 and/or -8 isoforms. Although the present disclosure relates generally to NHE3 binding compounds, compounds showing NHE-2 and/or -8 binding or inhibition are also of interest. However, while it is contemplated that suitable parent compounds may be a modification of known NHE3, -2 and/or -8 binding or inhibitory small molecules, small molecules identified to bind or inhibit other NHE subtypes, including NHE-1, may also be of interest. and can be optimized for selectivity and binding to the NHE3 subtype antiporter.

Suitable small molecules for use (i.e., suitable for use as essentially bioavailable compounds, suitable for modification or functionalization to produce a substantially systemically non-bioavailable compound) include those illustrated below. In this regard, it should be noted that a link to Z (ie, a modification or functionalization that renders small molecules substantially impermeable or substantially systemically non-bioavailable) is not specifically shown. As noted, the Z group may be attached to, or incorporated into, the small molecule at essentially any site or position that does not interfere (eg, sterically) with the ability of the resulting compound to effectively bind to the target NHE antiport. More specifically, Z can be attached to essentially any site on the NHE-binding small molecule, with Z, for example, replacing all or part of the substituent originally present, as illustrated below, provided that the site of attachment of the Z group does not substantially adversely affect for NHE binding activity. In one particular embodiment, however, the bond is located from Z to a site on the small molecule that effectively establishes the site of attachment at that distance (based, for example, on the number of intermediate atoms or bonds) from the atom or atoms present in the final compound, which effectively acts as a sodium ion mimetic (eg, an atom or atoms capable of forming a positive ion under physiological conditions). In a preferred embodiment, the bond extends from Z to a site in the ring, and more preferably the aromatic ring, within the small molecule that serves as the backbone.

In view of the foregoing, in one particular embodiment, the following small molecule disclosed in U.S. Patent Application 2005/0054705, the entire contents of which (and in particular the text of pages 1-2) are incorporated herein by reference for all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable).

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference. In one particularly preferred embodiment, R₆ and R₇ denote a halogen (e.g. Cl), R_five stands for lower alkyl (for example, CH₃) and R₁-R_four denote H, and the compound has, for example, the structure:

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 1-2) are incorporated herein in all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable).

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire content of which (and in particular page 49) is incorporated herein in all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable).

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 118-120 and 175-177) are incorporated herein description, for all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (e.g., associated with or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable ).

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 129-131) are incorporated herein in all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable).

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference. (In this regard, it should be noted that the Z substituent in the structure illustrated above should not be confused with the Z group, which, in accordance with the present disclosure, is attached to the NHE-binding small molecule in order to effectively make the resulting "NHE-Z "essentially impenetrable).

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 127-129) are incorporated herein in all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable).

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference. (In this regard, it should be noted that the Z within the ring of the structure illustrated above should not be confused with the Z group, which, according to the present disclosure, is attached to an NHE-binding small molecule in order to effectively make the resulting "NHE-Z "essentially impenetrable).

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 134-137) are incorporated herein in all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable).

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 31-32 and 137-139) are incorporated herein description, for all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (e.g., associated with or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable ).

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 37-45) are incorporated herein in all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable).

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference. (In this regard, it should be noted that the Z in the ring structure illustrated above should not be confused with the Z group, which, according to the present disclosure, is attached to an NHE-binding small molecule in order to effectively make the resulting "NHE-Z "essentially impenetrable).

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 100-102) are incorporated herein in all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable).

Variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference (in which, in particular, wavy bonds indicate a variable length or a variable number of atoms).

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 90-91 there) are incorporated herein in all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (for example, associated with or modified to include Z, so that the resulting NHE-Z molecule is essentially impermeable or essentially systemically non-bioavailable).

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in US Pat. and related purposes, may be suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable).

The variables in these structures are defined in the cited patents, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 35-47) are incorporated herein in all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable).

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 154-155) are incorporated herein in all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable).

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 132-133) are incorporated herein in all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable).

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 58-65 and 141-148) are incorporated herein description, for all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (e.g., associated with or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable ).

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference. (In this regard, it should be noted that the Z in the ring structure illustrated above should not be confused with the Z group, which, according to the present disclosure, is attached to an NHE-binding small molecule in order to effectively make the resulting "NHE-Z "essentially impenetrable).

In yet another specific embodiment, the following small molecule disclosed in US Pat. ) is incorporated herein by reference for all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (e.g., associated with or modified to include Z such that the resulting NHE-Z molecule is essentially impermeable or essentially systemically non-bioavailable).

The variables in this structure are defined in the cited patents, the details of which are incorporated herein by reference. A particularly preferred small molecule falling under the above structure is further illustrated below (see, for example, Example 1 of patent 6,911,453, the entire contents of which are hereby incorporated by reference):

In yet another particular embodiment, the following small molecules disclosed in US Patent Publications 2004/0039001, 2004/0224965, 2005/0113396, and 2005/0020612, all of which are incorporated herein by reference for all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable).

Variables in these structures are defined above and/or in one or more of the cited patent applications, the details of which are incorporated herein by reference, and/or as illustrated above (with broken links indicating the point of attachment of the Y group to the fused heterocyclic ring). In particular, in various embodiments, the combination of X and Y may be as follows:

In a particularly preferred embodiment of the above structure, the small molecule has the general structure:

in which R₁, R₂ and R₃ may be the same or different, but preferably are different and are independently selected from H, NR'R'' (wherein R' and R'' are independently selected from H and hydrocarbyl such as lower alkyl as defined elsewhere herein), and structure:

In a more preferred embodiment of the above structure, a small molecule falling within the above structure is further illustrated below (see, for example, the compound on page 5 of patent application 2005/0020612, the entire contents of which are specifically incorporated herein by reference) :

In another particularly preferred embodiment, the following small molecule disclosed in US Pat. modifications in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is essentially impermeable or essentially systemically non-bioavailable).

In this structure, R may preferably be selected from H and (CH ₃ ) ₂ NCH ₂ CH ₂ - with H being particularly preferred in various embodiments.

In another particular embodiment, the following small molecule disclosed in US Pat. No. 6,005,010 (and in particular columns 1-3) and/or US Pat. the contents of which are incorporated herein by reference for all relevant and related purposes, may be suitable for use or modification in accordance with the present disclosure (for example, associated with or modified to include Z, such that the resulting NHE-Z molecule is essentially impermeable or essentially systemically non-bioavailable).

The variable ("R'') in this structure is defined in the cited patent application, the details of which are incorporated herein by reference.

In another particularly preferred embodiment, the following small molecule disclosed in US Patent Application 2008/0194621, the entire content of which (and in particular the text of Example 1) is incorporated herein by reference for all relevant and related purposes, may be particularly suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or essentially systemically non-bioavailable).

The variables ("R ₁ ", "R ₂ and "R ₃ ") in this structure are as defined above and/or as defined in the cited patent application, the details of which are incorporated herein by reference.

In another particularly preferred embodiment, the following small molecule disclosed in US Patent Application 2007/0225323, the entire content of which (and in particular the text of Example 36) is incorporated herein by reference for all relevant and related purposes, may be particularly suitable for use or modification in accordance with the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or essentially systemically non-bioavailable).

In another particularly preferred embodiment, the following small molecule disclosed in US Pat. No. 6,911,453, the entire contents of which (and in particular the text of Example 35) is incorporated herein by reference for all relevant and related purposes, may be particularly suitable for use or modifications according to the present disclosure (eg, linked to or modified to include Z such that the resulting NHE-Z molecule is substantially impermeable or substantially systemically non-bioavailable).

In one particularly preferred embodiment of the present disclosure, the small molecule may be selected from the group consisting of:

In these structures, a bond (not shown) may be located, for example, between the Core and an amine-substituted aromatic ring (first structure), a heterocyclic ring or the aromatic ring to which it is bonded, or alternatively a chlorine-substituted aromatic ring (second structure) or a difluoro -substituted aromatic ring or sulfonamide-substituted aromatic ring (third structure).

D. Small Molecule Selectivity Examples

Shown below are examples of various NHE-binding small molecules and their selectivity among NHE-1, -2 and -3 isoforms. (See, for example, B. Masereel et al., An Overview of Inhibitors of Na + / H + Exchanger, European J. of Med. Chem., 38, pp. 547-554 (2003), the entire contents of which are incorporated herein link for all relevant and related purposes). Most of these small molecules have been optimized as NHE-1 inhibitors and this is reflected in their selectivity for it (IC _50s for subtype -1 are significantly more potent (digitally lower) than for subtype 3). However, the data in Table 2 shows that NHE3 binding activity can be projected into a range of compounds initially optimized against a different isoform. For example, amiloride is a weak NHE3 binder/inhibitor and was inactive against this antiporter at the highest concentration tested (IC ₅₀ > 100 μM); however, analogs of this compound, such as DMA and EIPA, have NHE3 IC _50s of 14 and 2.4 μM, respectively. Cinnamoylguanidine S-2120 is more than 500 times more active against NHE-1 than NHE3; however, this selectivity is completely reversed for the S-3226 regioisomer. Thus, it is possible to design NHE3-binding selectivity into a chemistry optimized against another antiporter isoform; that is, the classes of inhibitors exemplified in the art may be suitably modified in terms of activity and selectivity against NHE3 (or alternatively NHE-2 and/or NHE-8), as well as, if necessary, modified to provide substantially impermeable or essentially systemic non-bioavailability.

table 2

* = from rat, ** = from rabbit. NA = not active
^a Table adapted from Masereel, B. et al., European Journal of Medicinal Chemistry, 2003, 38, 547-54.
^b K _i values are shown in italics

As noted above, the NHE-binding small molecules disclosed herein, including those noted above, can be modified to render them essentially impermeable or essentially systemic non-bioavailable. The compounds described herein, respectively, effectively localize in the gastrointestinal tract or lumen, and in one particular embodiment, in the large intestine. Since different isoforms of NHE can be found in many different internal organs (e.g., brain, heart, liver, etc.), localization of NHE binding compounds in the intestinal lumen may be desirable in order to minimize or eliminate systemic effects (i.e., prevent or significantly limit the exposure of such organs to these compounds). Accordingly, the present disclosure relates to NHE binding compounds, and in particular to NHE3, -2 and/or -8 inhibitors, that are essentially systemically non-bioavailable in the GI tract, and more specifically, essentially systemically impermeable through the intestinal epithelium, as further described here.

E. Exemplary Embodiments

In one or more particularly preferred embodiments of the present disclosure, the "NHE-Z" molecule is monovalent; that is, the molecule contains one moiety that effectively binds to NHE3 and/or modulates NHE3 and also inhibits phosphate transport in the GI tract or kidney. In such embodiments, the NHE-Z molecule may be selected, for example, from one of the following structures of Formulas (IV), (V), (VI) or (VII):

in which: each R₁, R₂, R₃, R_five and R_nine independently selected from H, halogen (e.g. Cl), -NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H or Z, where Z is selected from substituted or unsubstituted hydrocarbyl, heterohydrocarbyl, polyalkylene glycol and polyhydric alcohols, where substituents are selected from hydroxyls, amines, amidines, carboxylates, phosphonates, sulfonates and guanidines; R_four selected from H, C₁-C₇ alkyl or Z, where Z is selected from substituted or unsubstituted hydrocarbyl, heterohydrocarbyl, polyalkylene glycol and polyhydric alcohols, where the substituents are selected from hydroxyls, amines, amidines, carboxylates, phosphonates, sulfonates and guanidines; R₆ missing or selected from H and C₁-C₇ alkyl; and Ar1 and Ar2 are independently an aromatic ring, or alternatively a heteroaromatic ring in which one or more carbon atoms have been replaced by an N, O, or S atom;

in which: each R₁, R₂, R₃ and R_five independently selected from H, -NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H or Z, where Z is selected from substituted or unsubstituted hydrocarbyl, heterohydrocarbyl, polyalkylene glycol and polyhydric alcohols, where the substituents are selected from hydroxyls, amines, amidines, carboxylates, phosphonates, sulfonates and guanidines, optionally linked to the Ar1 ring by a heterocyclic linker ; R_four and R₁₂ independently selected from H and R₇, where R₇ has the meanings defined above; R₁₀ and R_eleven, when present, are independently selected from H and C₁-C₇ alkyl; and Ar1 and Ar2 are independently an aromatic ring or, alternatively, a heteroaromatic ring in which one or more carbon atoms have been replaced by an N, O, or S atom;

or

in which: each X denotes a halogen atom, which may be the same or different; R₁ selected from -SO₂-NR₇R₈, -NR₇(CO)R₈, -(CO)NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H or Z, where Z is selected from substituted or unsubstituted hydrocarbyl, heterohydrocarbyl, polyalkylene glycol and polyhydric alcohols, where substituents are selected from hydroxyls, amines, amidines, carboxylates, phosphonates, sulfonates and guanidines; R₃ selected from H or R₇, where R₇ has the meanings as described above; R₁₃ selected from substituted or unsubstituted C₁-C₈ alkyl; R₂ and R₁₂ independently selected from H or R₇, and R₇ has the meanings as described above; R₁₀ and R_eleven, when present, are independently selected from H and C₁-C₇ alkyl; Ar1 is an aromatic ring, or alternatively a heteroaromatic ring in which one or more carbon atoms have been replaced by an N, O or S atom; and Ar2 is an aromatic ring, or alternatively a heteroaromatic ring, in which one or more carbon atoms have been replaced by an N, O, or S atom.

In one particular embodiment, for the structure of Formula (V), one of R₁, R₂ and R₃ linked to the Ar1 ring, and/or R_five linked to the Ar2 ring, a heterocyclic linker having the structure:

in which R stands for R₁, R₂, R₃ or R_fiveassociated with it.

In another particular embodiment, the NHE-Z molecule according to the present disclosure may have the structure of Formula (IV):

in which: each R₁, R₂, R₃, R_five and R_nine independently selected from H, halogen, NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H or Z, where Z is selected from substituted hydrocarbyl, heterohydrocarbyl or polyhydric alcohols and/or substituted or unsubstituted polyalkylene glycol, and the substituents are selected from the group consisting of phosphinates, phosphonates, phosphonamidates, phosphates, phosphonthioates and phosphonodithioates; R_four selected from H or Z, where Z denotes a substituted or unsubstituted hydrocarbyl, heterohydrocarbyl, polyalkylene glycol and polyhydric alcohol, where the substituents are selected from hydroxyls, amines, amidines, carboxylates, phosphonates, sulfonates and guanidines; R₆ selected from -H and C₁-C₇ alkyl; and Ar1 and Ar2 are independently an aromatic ring, or alternatively a heteroaromatic ring in which one or more carbon atoms have been replaced by an N, O, or S atom.

Additionally, or alternatively, in one or more embodiments of the compounds illustrated above, the compound may optionally have a tPSA of at least about 100 Å ² , about 150 Å ² , about 200 Å ² , about 250 Å ² , about 270 Å ² . or greater and/or a molecular weight of at least about 710 Da.

F. Polyvalent structures: Macro-molecules and oligomers

(i). General structure

As noted above, some embodiments relate to NHE-linked small molecules that have been structurally modified or functionalized to change their physicochemical properties (addition or incorporation of a Z group), and more specifically, the physicochemical properties of the NHE-Z molecule, thus rendering it substantially impermeable or substantially systemically non-bioavailable. In one particular embodiment, and as further detailed elsewhere in the description, the NHE-Z compound may be a polyvalent (i.e., oligomeric, dendrimeric, or polymeric unit), wherein Z may be referred to in this embodiment generally as a "Central" group, and the NHE-binding small molecule can be linked to it directly or indirectly (through a linking group), with polyvalent compounds having, for example, one of the following general structures of Formula (VIII), (IX) and (X):

in which: Core (or Z) and NHE have the meanings defined above; L is a bond or linker as defined elsewhere in the description below, and E and n are both an integer of 2 or greater. In various alternative embodiments, however, the NHE-binding small molecule can be rendered substantially impermeable or substantially systemically non-bioavailable by forming a polymeric structure from a plurality of NHE-bound small molecules, which may be the same or different, attached or linked by a series of linkers, L , which may also be the same or different, the compound having, for example, the structure of Formula (XI):

where: Core (or Z) and NHE have the meanings defined above; L is a bond or linker, as defined elsewhere in the description below, and m is 0 or an integer of 1 or greater. In this embodiment, the physicochemical properties, and in particular the molecular weight or polar surface area, of the NHE-binding small molecule are modified (e.g., increased) by having a number of NHE-binding small molecules bound together, making them substantially impermeable. or essentially systemically non-bioavailable. In these or other alternative embodiments, the polyvalent compound may be in dimeric, oligomeric, or polymeric form, wherein, for example, Z or Core is a scaffold to which are attached (via a linker, for example) a plurality of NHE-binding small molecules. Such compounds may have, for example, the structures of Formulas (XIIA) or (XIIB):

,

,

in which: L denotes a linking group; NHE refers to an NHE-binding small molecule, each NHE being as described above and in further detail hereinafter; and n means an integer other than zero (ie, integer 1 or greater).

The core group Core has one or more attachment sites to which NHE-binding small molecules are attached, and preferably covalently attached, via a bond or linker, L. The core group can, in general, be anything that makes a complete connection essentially impermeable or substantially systemically non-bioavailable (e.g., atom, small molecule, etc.), but in one or more preferred embodiments, is an oligomeric, dendrimeric, or polymeric group, in each case having more than one attachment site for L (and thus way for an NHE-binding small molecule). The combination of the main group and the NHE-binding small molecule (ie, the "NHE-Z" molecule) may have physico-chemical properties that render the entire bond substantially impermeable or substantially systemically non-bioavailable.

In this regard, it should be noted that the repeating unit in Formulas (XIIA) and (XIIB) generally covers the repeating units of various polymeric embodiments, which can, if necessary, be obtained by the methods described here. In each polymeric, or more generally polyvalent, embodiment, it should be noted that each repeat unit may be the same or different, and may or may not be linked to an NHE-binding small molecule linker, which in turn may be the same or different. when present. In this regard, it should be noted that, within the meaning of the invention, "polyvalent" refers to a molecule that has multiple (eg, 2, 4, 6, 8, 10 or more) NHE-binding groups.

The above-mentioned known embodiments are further illustrated below. For example, the first formula below of an example of an oligomeric compound in which the various parts of a compound corresponding to the structure of Formula (X) are identified is intended to provide a broad context for the disclosure herein. It should be noted that while each "NHE" group (ie, small NHE molecule) in the structure below is the same, it is for the purposes of this disclosure that each is independently selected and may be the same or different. In the illustration below, the linker group is a polyethylene glycol (PEG) unit. PEG derivatives are preferred due in part to their water solubility, which can help avoid hydrophobic collapse (an intramolecular interaction of hydrophobic units that can occur when a hydrophobic molecule is exposed to an aqueous environment (see, for example, Wiley, RA; Rich, DH Medical Research Reviews 1993, 13(3), 327-384) The core group illustrated below is also preferred because it imparts some rigidity to the Core-(L-NHE) _n molecule, allowing for increased spacing between NHE-bonding compounds while minimizing the increase in rotational degrees of freedom. .

In an alternative embodiment (eg, Formula (XI) in which m = 0), the structure may be, for example, the following:

In the composition of the polyvalent compounds used for treatment according to the present disclosure, n and m (when m is other than zero) can be independently selected from the range from about 1 to about 10, more preferably from about 1 to about 5, and even more preferably from about 1 to about 2. In alternative embodiments, however, n and m can be independently selected from the range of from about 1 to about 500, preferably from about 1 to about 300, more preferably from about 1 to about 100, and most preferably from about 1 to about 50. In these or other particular embodiments, n and m can both be within the range of about 1 to about 50, or about 1 to about 20.

The structures above are illustrative of one embodiment of compounds used for administration in which absorption is limited (i.e., the compound is substantially impermeable or substantially systemically non-bioavailable) by increasing the molecular weight of the NHE-binding small molecule. In a further embodiment, as noted elsewhere in the specification, the NHE-binding small molecule can be made substantially impermeable, or substantially systemically non-bioavailable, by altering, and more specifically increasing, the topological polar surface area, as further illustrated by the following structures, in which the substituted aromatic the ring is linked to the backbone of an NHE-binding small molecule. The choice of ionic groups such as phosphonates, sulfonates, guanidines, and the like can be particularly advantageous in preventing paracellular permeability. Carbohydrates are also preferred and, although they are uncharged, significantly increase tPSA with a minimal increase in molecular weight.

It should be noted that in one or more of the various embodiments illustrated herein, NHE-binding small molecules suitable for use (i.e., suitable for use as substantially bioavailable compounds, suitable for modification or functionalization to render them substantially impermeable or essentially systemically non-bioavailable) may in particular be independently selected from one or more of the small molecules described as benzoylguanidines, heteroaroylguanidines, "spacer-stretched" aroylguanidines, nonacylguanidines, and acylguanidine isosteres discussed above and discussed in greater detail hereinafter, and/ or small molecules detailed in, for example: US5866610; US6399824; US6911453; US6703405; US6005010; US6887870; US6737423; US7326705; US 55824691 (WO94/026709); US6399824 (WO02/024637); US 2004/0339001 (WO02/020496); US 2005/0020612 (WO03/055490); WO01/072742; CA 2387529 (WO01021582); CA 02241531 (WO97/024113); US 2005/0113396 (WO03/051866); US2005/0020612; US2005/0054705; US2008/0194621; US2007/0225323; US2004/0039001; US2004/0224965; US2005/0113396; US2007/0135383; US2007/0135385; US2005/0244367; US2007/0270414; and CA 2177007 (EP0744397), all of which are incorporated herein by reference for all relevant and related purposes. Again, it should be noted that when it is said that the NHE-binding small molecule is independently selected, this means that, for example, the oligomeric structures represented in Formulas (X) and (XI) above may include various small structures NHE molecules within the same oligomer or polymer. In other words, each "NHE" within a given polyvalent embodiment may independently be the same or different from other "NHE" groups within the same polyvalent embodiment.

In designing and making substantially impermeable or substantially systemically non-bioavailable NHE binding compounds that can be used for the treatments detailed in this disclosure, it may in some cases be advantageous to first determine the likely site of attachment on the small molecule NHE binding compound where the central portion or a linker can be installed or attached before obtaining a number of multivalent or polyvalent candidate compounds. This can be done by one skilled in the art by systematically inserting functional groups or functional groups displaying a fragment of the desired core or linker into various positions of the NHE-binding small molecule and then testing these adducts to determine if the modified compound retains the desired biological properties. (eg binding and/or modulation of NHE3, inhibition of phosphate transport). Understanding the SAR of a compound also allows the design of cores and/or linkers that are positively involved in the activity of the resulting compounds. For example, the SAR of a number of NHE-binding compounds can show that the installation of an N-alkylated piperazine has a positive effect on biochemical activity (increased potential) or pharmaceutical properties (increased solubility); the piperazine group can then be used as the site of attachment for the desired central group or linker via N-alkylation. The resulting compound thus retains the favorable biochemical or pharmaceutical properties of the parent small molecule. In another example, the SAR of a number of NHE binding compounds may indicate that the hydrogen bond donor is important for activity or selectivity. The linker cores or groups can then be designed to retain this H-bond donor. These cores and/or linkers can be further designed to decrease or potentiate the pKa of the H-bond donor, potentially allowing for increased potency and selectivity. In another scenario, the aromatic ring in the compound may be an important pharmacophore, interacting with the biological target via a pi-stacking effect or pi-cation interaction. The linker and backbone units can likewise be designed to be isosteric or otherwise interact synergistically with the aromatic features of the small molecule. Accordingly, once structure-activity relationships within a molecular series are understood, target molecules can be disassembled into key pharmacophores that act as essential elements of molecular recognition. Considering the installation of a central or linker unit, said units can be designed to exploit this SAR and can be installed to be isosteric and isoelectronic with these units, resulting in compounds that retain biological activity but have significantly reduced permeability.

Another way in which the SAR of a number of compounds can be exploited in the installation of the central part or group of the linker is to understand which regions of the molecule are insensitive to structural transformations. For example, X-ray co-crystal structures of protein-targeted compounds can reveal those parts of the compound that are exposed to the solvent and do not participate in productive interactions with the target. Such regions can also be identified empirically when chemical modifications in these regions result in a "flat SAR" (i.e., the modifications have minimal visible contribution to biochemical activity). Specialists have often exploited such regions to engineer the pharmaceutical properties of a compound, for example, by installing links , which can increase the solubility or potentiate the properties of ADME.In the same way, such regions are expected to be advantageous installation sites for the core or linker group to obtain compounds, as described in this disclosure.These regions are also expected to be sites for attaching, for example, a very polar functional group such as carboxylic acids, phosphinic acids, sulfonic acids, and the like, to significantly increase tPSA.

Another aspect that must be considered when designing cores and linkers exhibiting NHE binding activity is to limit or prevent hydrophobic collapse. Compounds with extended hydrocarbon functional groups can collapse in an intramolecular manner, provoking an enhanced enthalpic barrier to interact with the desired biological target. Accordingly, when designing the cores and linkers, they are preferably designed to be resistant to hydrophobic collapse. For example, conformational constraints such as rigid monocyclic, bicyclic, or polycyclic rings can be placed in the core or linker to increase the rigidity of the structure. Unsaturated bonds such as alkenes and alkynes may also or alternatively be installed. Such modifications can make the NHE binding compound available for productive binding to the target. In addition, the hydrophilicity of linkers can be improved by the addition of hydrogen bond donor or acceptor units or ionic units such as amines, which are protonated in the gastrointestinal tract, or acids, which are deprotonated. Such modifications increase the hydrophilicity of the core or linker and help prevent hydrophobic collapse. In addition, such modifications also contribute to the impermeability of the resulting compounds, increasing tPSA.

Particular examples of NHE-binding small molecules modified in accordance with the principles detailed above are illustrated below. These groups show functional groups that facilitate their attachment to "Z" (for example, the main group, Core, or the linker group, L). These functional groups may include electrophiles, which can react with nucleophilic centers or linkers, and nucleophiles, which can react with electrophilic centers or linkers. Small molecule NHE-binding compounds can likewise be derivatized with, for example, boronic acid groups, which can then react with suitable central moieties or linkers via palladium-mediated cross-linking reactions. The NHE-binding compound may also contain olefins, which can then react with suitable centers or linkers via an olefin exchange chemistry, or alkynes or azides, which can then react with suitable centers or linkers via [2 + 3] cycloaddition. The skilled artisan may consider various functional groups that allow for easy and specific attachment of the NHE-binding small molecule to the desired core or linker. Examples of functionalized NHE derivatives include, but are not limited to, the following:

Scheme 1

Cinnamoylguanidine NHE linking group functionalized to show electrophilic or nucleophilic groups to facilitate reaction with cores and linkers

,

,

and the variables in the structures above (eg, R, etc.) have the meanings defined in US Pat. No. 6,399,824, the entire contents of which are incorporated herein by reference for all relevant and related purposes.

Scheme 2

Tetrahydroisoquinoline NHE linking group functionalized to show electrophilic or nucleophilic groups to facilitate reaction with cores and linkers

wherein the variables in the above structures (e.g., R _7-9 , etc.) have the meanings defined in US Pat. for all relevant and related purposes. See also Linz et al., Hypertension. 60:1560-7, 2012.

Scheme 3

Quinazoline NHE linking group functionalized to show electrophilic or nucleophilic groups to facilitate reaction with cores and linkers

wherein the variables in the structures above (e.g., R _7-9 , etc.) have the meanings defined in US 2005/0020612 and US 6,911,453, all of which (and in particular the text of columns 1-4 ) is incorporated herein by reference for all relevant and related purposes.

It should be noted that one skilled in the art can envision a variety of central or linker groups that can be functionalized with suitable electrophiles or nucleophiles. Shown below are a number of such compounds selected based on several design considerations, including solubility, steric effects, and their ability to confer, or compatibility with them, favorable structure-activity relationships. In this regard, it should be further noted, however, that the structures below and above are for illustrative purposes only and should therefore not be construed in a limiting sense.

Examples of electrophilic and nucleophilic linker groups include, but are not limited to, linker groups illustrated as follows:

Nucleophilic linkers (for use with electrophilic NHE inhibitory derivatives)

Electrophilic lin ceramics (for use with nucleophilic NHE inhibitory derivatives)

The linking group, L, in each of the described embodiments (including embodiments in which the NHE-binding small molecule is linked to a central moiety such as an atom, another small molecule, a polymeric group, an oligomeric group, or a non-repeating group) may be a chemical linker, such as a bond or another group, for example, containing from about 1 to about 200 atoms, or from about 1 to about 100 atoms, or from about 1 to about 50 atoms, which may be hydrophilic and/or hydrophobic. In one embodiment, the linking group may be a polymeric group that has been grafted onto a polymer backbone, for example, using living free radical polymerization approaches known in the art. Preferred L structures or groups may also be selected from, for example, oligoethylene glycol, oligopeptide, oligoethyleneimine, oligotetramethylene glycol and oligocaprolactone.

As noted, the main group may be an atom, small molecule, oligomeric, dendrimeric, or polymeric group, in each case having one or more attachment sites for L. For example, the main group may be a non-repetitive group (considered as a whole, including attachment sites to compounds) selected, for example, from the group consisting of alkyl, phenyl, aryl, alkenyl, alkynyl, heterocyclic, amine, ether, sulfide, disulfide, hydrazine, and any of the above, substituted with oxygen, sulfur, sulfonyl, phosphonyl, hydroxyl, alkoxy, amine, thiol, ether, carbonyl, carboxyl, ester, amide, alkyl, alkenyl, alkynyl, aryl, heterocyclic group, and groups including combinations thereof (in each permutation). A non-repeating group may include repeating units (eg, methylene) within its subdivisions or segments (eg, within an alkyl segment) without having the discrete repeat units that make up the group as a whole (eg, in the sense of a polymer or oligomer).

Examples of basic groups include, but are not limited to, the basic groups illustrated in the Examples, and ether groups, ester groups, sulfide groups, disulfide groups, amino groups, aryl groups, alkoxy groups, etc., such as, for example, the following:

, через них) представляют собой места присоединения либо к NHE-связывающему соединению, либо к линкерной группе, показывающей NHE-связывающее соединение, где указанные места присоединения могут быть получены с использованием химических реакций и функциональных групп, известных в области лекарственной химии; и причем каждый p, q, r и s означает независимо выбранное целое число в пределах от приблизительно 0 до приблизительно 48, предпочтительно от приблизительно 0 до приблизительно 36, или от приблизительно 0 до приблизительно 24, или от приблизительно 0 до приблизительно 16. В некоторых случаях, каждый p, q, r и s может быть независимо выбранным целым числом в пределах от приблизительно 0 до 12. Дополнительно, R может быть группой заместителя, в целом выбранной из галогенида, гидроксила, амина, тиола, простого эфира, карбонила, карбоксила, сложного эфира, амида, карбоциклической группы, гетероциклической группы и групп, включающих комбинации этого.moreover, broken connections (that is, those that have a wavy connection,

, through them) are attachment points either to an NHE binding compound or to a linker group indicating an NHE binding compound, where said attachment sites can be obtained using chemical reactions and functional groups known in the field of medicinal chemistry; and wherein each p, q, r, and s is an independently selected integer ranging from about 0 to about 48, preferably from about 0 to about 36, or from about 0 to about 24, or from about 0 to about 16. In some cases, each p, q, r, and s may be an independently selected integer ranging from about 0 to 12. Additionally, R may be a substituent group generally selected from halide, hydroxyl, amine, thiol, ether, carbonyl, carboxyl , an ester, an amide, a carbocyclic group, a heterocyclic group, and groups including combinations thereof.

In another approach, the core group is a dendrimer defined as a repeatedly branched molecule (see, e.g., J. M. J. Frechet, D. A. Tomalia, Dendrimers and Other Dendritic Polymers, John Wiley & Sons, Ltd. NY, NY, 2001) and represented in Figure 17.

In this approach, an NHE-binding small molecule is attached via an L to one, several, or optionally all, terminals located on the periphery of the dendrimer. In another approach, the structural element of the dendrimer, called the dendron and illustrated above, is used as the central part, and the NHE-linking group is attached to one, several or, if necessary, all the terminations located on the periphery of the dendron. The number of generations is typically from about 0 to about 6, and preferably from about 0 to about 3. (Generation is defined in, for example, J. M. J. Frechet, D. A. Tomalia, Dendrimers and Other Dendritic Polymers, John Wiley & Sons, Ltd. NY, NY) . Dendrimer and/or dendron structures are known in the art and include, for example, those shown or illustrated in: (i) J. M. J. Frechet, D. A. Tomalia, Dendrimers and Other Dendritic Polymers, John Wiley & Sons, Ltd. NY, NY; (ii) George R Newkome, Charles N. Moorefield and Fritz Vogtle, Dendrimers and Dendrons: Concepts, Syntheses, Applications, VCH Verlagsgesellschaft Mbh; and (iii) Boas, U., Christensen, J.B., Heegaard, P.M.H., Dendrimers in Medicine and Biotechnology: New Molecular Tools, Springer, 2006.

In another approach, the main group may be a polymeric group or an oligomeric group. The polymer or oligomer, in each case, may be considered independently and may include repeat units consisting of a repeat group selected from alkyl (eg, -CH ₂ -), substituted alkyl (eg, -CHR-, in which, for example, R is hydroxy), alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, phenyl, aryl, heterocyclic group, amine, ether, sulfide, disulfide, hydrazine, and any of the above substituted with oxygen, sulfur, sulfonyl, phosphonyl, hydroxyl, alkoxyl, amine , thiol, ether, carbonyl, carboxyl, ester, amide, alkyl, alkenyl, alkynyl, aryl, heterocyclic group, and groups including combinations thereof. In another approach, the core group includes repeat units resulting from the polymerization of ethylene monomers (eg, such as the ethylene monomers listed elsewhere in the description below).

Preferred polymers for polymer groups useful for constructing substantially impermeable or substantially systemically non-bioavailable NHE binding compounds that are polyvalent for use in the various treatments disclosed herein may be prepared by any suitable technique such as free radical polymerization, condensation polymerization, addition polymerization, ring opening polymerization, and/or can be derived from natural polymers such as saccharide polymers. Further, in some embodiments, any of these polymeric groups may be functionalized.

Examples of polysaccharides suitable for use in the preparation of such compounds include, but are not limited to, materials derived from vegetables or animals, including cellulose materials, hemicellulose, alkylcellulose, hydroxyalkylcellulose, carboxymethylcellulose, sulfoethylcellulose, starch, xylan, amylopectin, chondroitin, hyaluronate, heparin , guar, xanthan, mannan, galactomannan, chitin and/or chitosan. More preferred, at least in some cases, are polymeric groups that do not, or do not degrade to a significant extent, under the physiological conditions of the GI tract (such as, for example, carboxymethylcellulose, chitosan, and sulfoethylcellulose).

When free radical polymerization is used, the polymer group can be derived from various classes of monomers including, for example, acrylic, methacrylic, styrenic, vinyl, and diene, typified by the following: styrene, substituted styrene, alkyl acrylate, substituted alkyl acrylate, substituted alkyl methacrylate alkyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, N,N-dialkylacrylamide, N,N-dialkylmethacrylamide, methylbutadiene, butadiene, ethylene, vinyl acetate, and combinations thereof. Functionalized versions of these monomers may also be used, and any of these monomers may be used with other monomers as comonomers. For example, certain monomers or comonomers that may be used in this disclosure include methyl methacrylate, ethyl methacrylate, propyl methacrylate (all isomers), butyl methacrylate (all isomers), 2-ethylhexyl methacrylate, isobromyl methacrylate, methacrylic acid, benzyl methacrylate, phenyl methacrylate, methacrylonitrile, α-methylstyrene, methyl acrylate, ethyl acrylate, propyl acrylate (all isomers), butyl acrylate (all isomers), 2-ethylhexyl acrylate, isobromyl acrylate, acrylic acid, benzyl acrylate, phenyl acrylate, acrylonitrile, styrene, glycidyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate (all isomers), hydroxybutyl methacrylate (all isomers), N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, triethylene glycol methacrylate, itaconic anhydride, itaconic acid, glycidyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate (all isomers), hydroxybutyl acrylate (all isomers), N,N-dimethylaminoethyl acrylate, N,N-diethylaminoethyl acrylate, triethylene glycol acre ylate, methacrylamide, N-methylacrylamide, N,N-dimethylacrylamide, N-tert-butylmethacrylamide, N-n-butylmethacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-tert-butylacrylamide, N-n-butylacrylamide, N-methylacrylamide, N- ethylacrylamide, 4-acryloylmorpholine, vinylbenzoic acid (all isomers), diethylaminostyrene (all isomers), α-methylvinyl benzoic acid (all isomers), diethylamino α-methylstyrene (all isomers), p-vinylbenzene sulfonic acid, p-vinylbenzene sulfonic sodium salt acids, functional alkoxy and alkyl silane monomers, maleic anhydride, N-phenylmaleimide, N-butylmaleimide, butadiene, methyl butadiene, chloroprene, ethylene, vinyl acetate, vinyl formamide, allylamine, vinyl pyridines (all isomers), fluoroacrylate, methacrylates, and combinations thereof. Polymeric units with heteroatoms in the main chain can also be used, including polyethyleneimine and polyethers such as polyethylene oxide and polypropylene oxide, and their copolymers.

In one particular embodiment, the polymer to which the NHE-binding small molecule, NHE, is attached or otherwise forms a part is a polyhydric alcohol (e.g., a polymer having a repeating unit, e.g., a hydroxyl-substituted alkyl such as -CH(OH )-). Polyhydric alcohols, such as mono- and disaccharides, with or without reducing or reducible end groups, may be good candidates, for example, for the installation of an additional functional group, which can make the connection essentially impermeable.

In one particular embodiment, an NHE-binding small molecule, NHE, is attached at one or both ends of the polymer chain. More specifically, in yet another additional embodiment to the polyvalent embodiment of the present disclosure, a macromolecule (e.g., polymer or oligomer) having one of the following structures can be designed and produced as described here:

It should also be noted that the repeating group in Formulas (XIIA) or (XIIB) generally encompasses repeating units of polymers and copolymers obtained by the methods mentioned here above.

It should be noted that the various properties of the oligomers and polymers that form the core as disclosed herein above may be optimized for a given use or application using experimental means and principles well known in the art. For example, the total molecular weight of the compounds or structures presented herein above may be chosen to achieve nonabsorbability, persistence, and/or inhibition potential.

Additionally, with respect to those polymeric embodiments that encompass or include compounds generally represented by the structure of Formula (I) and/or disclosed, for example, in many of the patents and patent applications cited here (see, for example, US5866610; US6399824; US6911453; US6703405; US6005010; US6887870; US6737423; US7326705; US 55824691 (WO94/026709); US6399824 (WO02/024637); US 2004/0339001 (WO02/020496); US 2005/0020612 (WO03/055490); WO01/072742; СА 2387529 (WO01021582); СА 02241531 (WO97/024113); US 2005/0113396 (WO03/051866); US2005/0020612; US2005/0054705; US2008/0194621; US2007/0225323; US2004/0039001; US2004/0224965; US2005/0113396 ; US2007/0135383; US2007/0135385; US2005/0244367; US2007/0270414; and CA 2177007 (EP0744397), all contents of which are incorporated herein by reference for all relevant and related purposes), such as in which these compounds or structures are side molecules of the polymer base or chain, and the composition of the polymer th backbone or chain, as well as the overall size or molecular weight of the polymer and/or the number of side molecules present, may be selected according to various principles known in the art in view of the intended application or use.

With respect to the polymer composition of the NHE binder, it should be noted that a variety of polymers can be used, including, for example, synthetic and/or natural aliphatic, alicyclic and/or aromatic polymers. In preferred embodiments, the polymeric group is stable under the physiological conditions of the GI tract. By "stable" is meant that the polymeric group does not degrade or degrade to a significant extent or substantially degrade under the physiological conditions of the GI tract. For example, at least about 90%, preferably at least about 95%, and more preferably at least about 98%, and even more preferably at least about 99%, of the polymer group remains intact or intact after at least about 5 hours. , at least about 12 hours, at least about 18 hours, at least about 24 hours, or at least about 48 hours in the gastrointestinal tract. Stability in the gastrointestinal tract can be assessed using gastrointestinal mimetics, for example, gastric mimetics or intestinal mimetics of the small intestine, which approximate physiological conditions at one or more sites in the gastrointestinal tract.

The polymeric groups detailed herein for use as base groups may be hydrophobic, hydrophilic, amphiphilic, uncharged or non-ionic, negatively or positively charged, or a combination thereof. Additionally, the polymer architecture of the polymer group may be linear, grafted, comb, block, star and/or dendritic, preferably chosen so as to produce the desired solubility and/or stability characteristics as described above.

Additionally or alternatively, modifications to the NHE-binding small molecules can be made that increase tPSA, thus contributing to the impermeability of the resulting compounds. Such modifications preferably include the addition of di-anions such as phosphonates, malonates, sulfonates and the like, and polyhydric alcohols such as carbohydrates and the like. Examples of NHE derivatives with increased tPSA include, but are not limited to, the following:

(ii). Embodiment examples

In one or more specific preferred embodiments of the present disclosure, the "NHE-Z" molecule is polyvalent; that is, the molecule contains two or more groups that effectively bind to and/or modulate NHE3 as well as inhibit phosphate transport in the GI tract or kidney. In such embodiments, the NHE-Z molecule may be selected, for example, from one of the following Formulas (IV), (V), (VI) or (VII):

,

,

in which: each R₁, R₂, R₃, R_five and R_nine independently selected from H, halogen, -NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H or L, provided that at least one is L, where L is selected from the group consisting of substituted or unsubstituted hydrocarbyl, heterohydrocarbyl, polyalkylene glycol, and polyhydric alcohols, and where L links the repeating unit to at least one other a repeating unit and/or at least one other Basic group independently selected from substituted or unsubstituted hydrocarbyl, heterohydrocarbyl, polyalkylene glycol, polyhydric alcohols, polyamines or polyacrylamides, a polyvalent compound; R_four selected from H, C₁-C₇ alkyl or L, where L is as defined above; R₆ missing or selected from H and C₁-C₇ alkyl; and, Ar1 and Ar2 are independently an aromatic ring, or alternatively a heteroaromatic ring in which one or more carbon atoms have been replaced by a N, O or S atom;

,

,

in which R₁, R₂, R₃ and R_fiveif necessary linked to the Ar1 ring by a heterocyclic linker and additionally independently selected from H, -NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H or L, provided that at least one is L, where L is selected from the group consisting of substituted or unsubstituted hydrocarbyl, heterohydrocarbyl, polyalkylene glycol, and polyhydric alcohols, and where L links the repeating unit to at least one other a repeating unit and/or at least one other Basic group independently selected from substituted or unsubstituted hydrocarbyl, heterohydrocarbyl, polyalkylene glycol, polyhydric alcohols, polyamines or polyacrylamides, a polyvalent compound; R_four and R₁₂ independently selected from H or L, where L is as defined above; R₁₀ and R_eleven, when present, are independently selected from H and C₁-C₇ alkyl; and Ar1 and Ar2 are independently an aromatic ring or, alternatively, a heteroaromatic ring in which one or more carbon atoms are replaced by an N, O, or S atom;

,

,

in which: each X denotes a halogen atom, which may be the same or different; R₁ selected from -SO₂-NR₇R₈, -NR₇(CO)R₈, -(CO)NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H or L, provided that at least one is L, where L is selected from the group consisting of substituted or unsubstituted hydrocarbyl, heterohydrocarbyl, polyalkylene glycol, and polyhydric alcohols, and where L links the repeating unit to at least one other a repeating unit and/or at least one other Basic group independently selected from substituted or unsubstituted hydrocarbyl, heterohydrocarbyl, polyalkylene glycol, polyhydric alcohols, polyamines or polyacrylamides, a polyvalent compound; R₃ selected from H or L, where L is as defined above; R₁₃ selected from substituted or unsubstituted C₁-C₈ alkyl; R₂ and R₁₂ independently selected from H or L, L having the meanings as described above; R_eleven and R₁₂, when present, independently selected from H and C₁-C₇ alkyl; Ar1 denotes an aromatic ring or, alternatively, a heteroaromatic ring in which one or more carbon atoms are replaced by a N, O or S atom; and Ar2 is an aromatic ring, or alternatively a heteroaromatic ring, in which one or more carbon atoms have been replaced by an N, O, or S atom.

In one particular embodiment, for the structure of Formula (V), one of R₁, R₂ and R₃ linked to the Ar1 ring and/or R_five linked to the Ar2 ring by a heterocyclic linker having the structure:

,

,

in which R stands for R₁, R₂, R₃ or R_fiveassociated with it.

In one particular embodiment, the NHE-binding small molecule has the structure of Formula (IV):

or a stereoisomer, prodrug or pharmaceutically acceptable salt thereof, wherein: each R₁, R₂, R₃, R_five and R_nine independently selected from H, halogen, -NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H or a bond linking the NHE-binding small molecule to L, provided that at least one is a bond linking the NHE-binding small molecule to L; R_four selected from H, C₁-C₇ alkyl or a bond linking the NHE-linking small molecule to L; R₆ missing or selected from H and C₁-C₇ alkyl; and Ar1 and Ar2 are independently an aromatic ring or a heteroaromatic ring.

In other particular embodiments of the above embodiment, the NHE-binding small molecule has the following structure:

or a stereoisomer, prodrug or pharmaceutically acceptable salt thereof, wherein: each R₁, R₂ and R₃ independently selected from H, halogen, -NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H or a bond linking the NHE-binding small molecule to L, provided that at least one is a bond linking the NHE-binding small molecule to L.

In one embodiment, the compound has the structure of Formula (X):

In other particular embodiments of the above embodiment, the NHE-binding small molecule has one of the following structures:

or a stereoisomer, prodrug or pharmaceutically acceptable salt thereof.

In other particular embodiments of the above embodiment, L is a polyalkylene glycol linker, such as a polyethylene glycol linker.

In other particular embodiments of the above embodiment, n = 2.

In other particular embodiments of the above embodiment, the Central part has the following structure:

,

,

in which: X is selected from the group consisting of a bond, -O-, -NH-, -S-, C _1-6 alkylene, -NHC(=O)-, -C(=O)NH-, -NHC( =O)NH-, -SO ₂ NH- and -NHSO ₂ -; Y is selected from the group consisting of a bond, optionally substituted C _1-6 alkylene, optionally substituted aryl, optionally substituted heteroaryl, polyethylene glycol linker, -(CH ₂ ) _1-6 O(CH ₂ ) _1-6 - and -(CH ₂ ) _1-6 NY ₁ (CH ₂ ) _1-6 -; and Y ₁ is selected from the group consisting of hydrogen, optionally substituted C _1-6 alkyl, optionally substituted aryl, or optionally substituted heteroaryl.

In other particular embodiments of the above embodiment, the Central part is selected from the group consisting of:

H. General Structure of Other Compound Examples

In one embodiment, the compounds of the present disclosure may be generally represented by Formula (I-H):

or a stereoisomer, prodrug or pharmaceutically acceptable salt thereof, wherein: (i) NHE is an NHE-binding and/or modulating small molecule group as defined below, (ii) n is an integer of 2 or greater, (iii) Core is a Core a group having two or more sites for attachment to two or more NHE binding small molecule groups, and (iv) L is a bond or linker connecting the Core to two or more NHE binding small molecule groups, wherein the resulting NHE binding compound (ie, the compound of Formula (I)) generally has physicochemical properties that render it substantially impermeable or substantially systemically non-bioavailable. The core group may be linked to essentially any position on, or within, the NHE-binding small molecule group, provided that its installation does not significantly adversely affect the NHE-binding activity.

It should be noted that in many of the structures illustrated here, all the various relationships are not shown in every case. For example, in one or more of the structures illustrated above, connections or bonds between the NHE-binding small molecule group and the Main group are not always shown. However, this should not be considered in a limiting sense. Rather, it should be understood that the NHE-binding small molecule is bound or attached in some way (e.g., by a bond or some kind of linker) to the backbone, such that the resulting NHE-binding compound is suitable for use (i.e., substantially impermeable or substantially systemically non-bioavailable in the GI tract).

Groups of NHE-binding small molecules suitable for use (i.e., suitable for modification or functionalization in accordance with the present disclosure) in the preparation of substantially impermeable or substantially systemically non-bioavailable NHE-binding compounds of the present disclosure are disclosed in WO2010/025856, the entire content which is incorporated herein by reference for all relevant and related purposes, and has the following structure Formulas (X-H):

.

.

Structure variables are defined in WO2010/025856, the details of which are incorporated herein by reference.

In more specific embodiments, the NHE-binding small molecule group has the following structure of Formula (XI-H):

,

,

in which: B is selected from the group consisting of aryl and heterocyclyl; every R_five independently selected from the group consisting of hydrogen, halogen, optionally substituted with C₁-FROM_four alkyl, optionally substituted with C₁-FROM_four alkoxy, optionally substituted with C₁-FROM_four thioalkyl, optionally substituted heterocyclyl, optionally substituted heterocyclylalkyl, optionally substituted aryl, optionally substituted heteroaryl, hydroxyl, oxo, cyano, nitro, -NR₇R₈, -NR₇C(=O)R₈, -NR₇C(=O)OR₈, -NR₇C(=O)NR₈R_nine, -NR₇SO₂R₈, -NR₇S(O)₂NR₈R_nine, -C(=O)OR₇, -C(=O)R₇, -C(=O)NR₇R₈, -S(O)_1-2R₇ and -SO₂NR₇R₈, and R₇, R₈ and R_nine independently selected from the group consisting of hydrogen, C_1-4alkyl or a bond linking the NHE-linking small molecule group to L, provided that at least one is a bond linking the NHE-linking small molecule group to L; R₃ and R_four independently selected from the group consisting of hydrogen, optionally substituted with C_1-4alkyl, optionally substituted cycloalkyl, optionally substituted cycloalkylalkyl, optionally substituted aryl, optionally substituted aralkyl, optionally substituted heterocyclyl and optionally substituted heteroaryl; or R₃ and R_four together with the nitrogen to which they are attached, form, if necessary, a substituted 4-8 membered heterocyclyl; and every R₁ independently selected from the group consisting of hydrogen, halogen, optionally substituted with C_1-6alkyl and optionally substituted C_1-6alkoxy.

In even more specific embodiments, the NHE-binding small molecule group has the following structure of Formula (XII-H):

,

,

in which: each R₃ and R_four independently selected from the group consisting of hydrogen and optionally substituted C_1-4alkyl, or R₃ and R_four, together with the nitrogen to which they are attached, form, if necessary, a substituted 4-8 membered heterocyclyl; every R₁ independently selected from the group consisting of hydrogen, halogen, C_1-6alkyl and C_1-6haloalkyl; and R_five selected from the group consisting of -SO₂-NR₇- and -NHC(=O)NH-, in which R₇ stands for hydrogen or C_1-4alkyl.

In various alternative embodiments, the NHE binding small molecule moiety can be made substantially impermeable or substantially systemically non-bioavailable by forming a polymeric structure from a plurality of NHE binding small molecule moieties, which may be the same or different, linked or attached by a series of linkers, L , which can also be the same or different, and the compound has, for example, the structure of Formula (II-H):

,

,

in which: NHE has the meanings defined above; L is a bond or linker as defined elsewhere in the description; and m is 0 or an integer 1 or greater. In this embodiment, the physicochemical properties, and in particular the molecular weight or polar surface area of the NHE-binding small molecule group, are modified (e.g., increased) in the presence of a number of NHE-binding small molecule groups to make them substantially impermeable or essentially systemically non-bioavailable.

In further alternative embodiments, the polyvalent NHE binding compound may be in oligomeric or polymeric form in which the backbone is linked (via a linker, for example) to a plurality of NHE binding small molecule groups. Such compounds may have, for example, the structures of Formulas (IIIA-H) or (IIIB-H):

,

,

in which: NHE has the meanings defined above; L denotes a bond or linker, as further defined elsewhere in the description; and n means an integer other than zero (ie, integer 1 or greater). It should be noted that the repeating unit in Formulas (IIIA-H) and (IIIB-H) generally encompasses the repeating units of various polymeric embodiments, including linear, branched and dendritic structures, which can, if necessary, be obtained by the methods mentioned here. In each polymeric, or more generally polyvalent, embodiment, it should be noted that each repeat unit may be the same or different, and may or may not be linked to the NHE-binding small molecule moiety by a linker, which in turn, when present, may be the same or different. In this regard, it should be noted that, within the meaning of the invention, "polyvalent" refers to a molecule that has multiple (eg, 2, 4, 6, 8, 10 or more) groups of NHE-binding small molecules.

In prior polyvalent embodiments, L may be a polyalkylene glycol linker such as a polyethylene glycol linker; and/or the Central part may have the following structure:

,

,

in which: X is selected from the group consisting of bond, -O-, -NH-, -S-, C _1-6 alkylene, -NHC(=O)-, -C(=O)NH-, -NHC( =O)NH-, -SO ₂ NH- and -NHSO ₂ -; Y is selected from the group consisting of a bond, optionally substituted C _1-6 alkylene, optionally substituted aryl, optionally substituted heteroaryl, polyethylene glycol linker, -(CH ₂ ) _1-6 O(CH ₂ ) _1-6 - and -(CH ₂ ) _1-6 NY ₁ (CH ₂ ) _1-6 -; and Y ₁ is selected from the group consisting of hydrogen, optionally substituted C _1-6 alkyl, optionally substituted aryl, or optionally substituted heteroaryl. For example, in some embodiments, the Central part may be selected, for example, from the group consisting of:

In other more specific embodiments, the Central part may be selected, for example, from the group consisting of:

The above embodiments are further illustrated below. For example, the first presentation of an example of an oligomeric compound below, in which various portions of the compound are identified, provides a broad context for the disclosure herein. It should be noted that while each NHE-binding small molecule in the structure below is the same, it is within the scope of this disclosure that each is independently selected and may be the same or different. In the illustration below, the linker group is a polyethylene glycol (PEG) unit. PEG derivatives are preferred due in part to their water solubility, which can help avoid hydrophobic collapse (an intramolecular interaction of hydrophobic units that can occur when a hydrophobic molecule is exposed to an aqueous environment (see, for example, Wiley, R. A.; Rich, D. H. Medical Research Reviews 1993, 13(3), 327-384) The main group illustrated below is also preferred because it imparts some rigidity to the molecule, allowing the spacing between NHE-binding small molecules to be increased while minimally increasing rotational degrees of freedom.

In an alternative embodiment, in which m = 0, the structure may be, for example:

In the composition of the polyvalent compounds used for the treatments of the present disclosure, n and m (when m is not zero) can be independently selected from the range of from about 1 to about 10, more preferably from about 1 to about 5, and even more preferably from about 1 to about 2. In alternative embodiments, however, n and m can be independently selected from the range of from about 1 to about 500, preferably from about 1 to about 300, more preferably from about 1 to about 100, and most preferably from about 1 to about 50. In these or other particular embodiments, E, n, and m may range from about 1 to about 50, or from about 1 to about 20.

In designing and making substantially impermeable or substantially systemically non-bioavailable NHE binding compounds that can be used for the treatments detailed in this disclosure, it may in some cases be advantageous to first determine the likely site of attachment on the group of the NHE binding small molecule where the central the part or linker can be installed or attached, before creating a set of candidate multivalent or polyvalent compounds. This can be done by one skilled in the art by systematically inserting functional groups or functional groups showing a moiety of the desired core or linker into different group positions of the NHE-binding small molecule and then testing these adducts to determine if the modified compound retains the desired biological properties. (eg NHE binding activity). Understanding the SAR of a compound also allows the design of cores and/or linkers that positively affect the activity of the resulting compounds.

Another aspect to be considered in the design of the cores and linkers is the limitation or prevention of hydrophobic collapse. Compounds with extended hydrocarbon functional groups can collapse onto themselves in an intramolecular manner, resulting in an increased enthalpy barrier to interaction with the desired biological target. Accordingly, when designing the cores and linkers, they are preferably designed to be resistant to hydrophobic collapse. For example, conformational constraints such as rigid monocyclic, bicyclic, or polycyclic rings can be placed in the core or linker to increase the rigidity of the structure. Unsaturated bonds such as alkenes and alkynes may also or alternatively be installed. Such modifications can make the NHE binding compound available for productive binding to the target. In addition, the hydrophilicity of linkers can be improved by the addition of hydrogen bond donor or acceptor units or ionic units such as amines, which are protonated in the gastrointestinal tract, or acids, which are deprotonated. Such modifications increase the hydrophilicity of the core or linker and help prevent hydrophobic collapse. In addition, such modifications also contribute to the impermeability of the resulting compounds, increasing tPSA.

The person skilled in the art may consider various functional groups that allow for easy and specific attachment of the NHE-binding small molecule to the desired core or linker. These functional groups may include electrophiles, which can react with nucleophilic centers or linkers, and nucleophiles, which can react with electrophilic centers or linkers. Small molecule NHE-binding compounds can likewise be derivatized with, for example, boronic acid groups, which can then react with suitable central moieties or linkers via palladium-mediated cross-linking reactions. The NHE-binding compound may also contain olefins, which can then react with suitable centers or linkers via an olefin exchange chemical reaction, or alkynes or azides, which can then react with suitable centers or linkers via [2 + 3] cycloaddition.

It should be noted that one skilled in the art can envision a variety of central or linker groups that can be functionalized with suitable electrophiles or nucleophiles. A number of such compounds are shown below, selected based on several design considerations, including solubility, steric effects, and their ability to confer, or compatibility with them, favorable structure-activity relationships. In this regard, it should be further noted, however, that the structures below and above are for illustrative purposes only and should therefore not be construed in a limiting sense.

Examples of electrophilic and nucleophilic linker groups include, but are not limited to, linker groups illustrated as follows:

Nucleophilic linkers (for use with electrophilic NHEs)

Electrophilic linkers (for use with nucleophilic NHEs)

The linking group, L, in each of the described embodiments (including embodiments in which the NHE-binding small molecule is linked to a central moiety such as an atom, another small molecule, a polymeric group, an oligomeric group, or a non-repeating group), may be a chemical linker, such as a bond or other group, for example, containing from about 1 to about 200 atoms, or from about 1 to about 100 atoms, or from about 1 to about 50 atoms, which may be hydrophilic and/or hydrophobic. In one embodiment, the linking group may be a polymeric group that has been grafted onto a polymer backbone, for example, using living free radical polymerization approaches known in the art. Preferred L structures or groups may also be selected from, for example, oligoethylene glycol, oligopeptide, oligoethyleneimine, oligotetramethylene glycol and oligocaprolactone.

As noted, the main group may be an atom, small molecule, oligomeric, dendrimeric, or polymeric group, in each case having one or more attachment sites for L. For example, the main group may be a non-repetitive group (considered as a whole, including attachment sites to compounds) selected, for example, from the group consisting of alkyl, phenyl, aryl, alkenyl, alkynyl, heterocyclic, amine, ether, sulfide, disulfide, hydrazine, and any of the above, substituted with oxygen, sulfur, sulfonyl, phosphonyl, hydroxyl, alkoxy, amine, thiol, ether, carbonyl, carboxyl, ester, amide, alkyl, alkenyl, alkynyl, aryl, heterocyclic group, and groups including combinations thereof (in each permutation). A non-repeating group may include repeating units (eg, methylene) within its subdivisions or segments (eg, within an alkyl segment) without having the discrete repeat units that make up the group as a whole (eg, in the sense of a polymer or oligomer).

Examples of basic groups include, but are not limited to, the basic groups illustrated in the Examples, and ether groups, ester groups, sulfide groups, disulfide groups, amino groups, aryl groups, alkoxy groups, etc., such as, for example, the following:

, через них) представляют собой места присоединения либо к NHE-связывающему соединению, либо к линкерной группе, показывающей NHE-связывающее соединение, где указанные места присоединения могут быть получены с использованием химических реакций и функциональных групп, известных в области лекарственной химии; и причем каждый p, q, r и s означает независимо выбранное целое число в пределах от приблизительно 0 до приблизительно 48, предпочтительно от приблизительно 0 до приблизительно 36, или от приблизительно 0 до приблизительно 24, или от приблизительно 0 до приблизительно 16. В некоторых случаях, каждый p, q, r и s может быть независимо выбранным целым числом в пределах от приблизительно 0 до 12. Дополнительно, R может быть группой заместителя, в целом выбранной из галогенида, гидроксила, амина, тиола, простого эфира, карбонила, карбоксила, сложного эфира, амида, карбоциклической группы, гетероциклической группы и групп, включающих комбинации этого.moreover, broken connections (that is, those that have a wavy connection,

, through them) are attachment points either to an NHE binding compound or to a linker group indicating an NHE binding compound, where said attachment sites can be obtained using chemical reactions and functional groups known in the field of medicinal chemistry; and wherein each p, q, r, and s is an independently selected integer ranging from about 0 to about 48, preferably from about 0 to about 36, or from about 0 to about 24, or from about 0 to about 16. In some cases, each p, q, r, and s may be an independently selected integer ranging from about 0 to 12. Additionally, R may be a substituent group generally selected from halide, hydroxyl, amine, thiol, ether, carbonyl, carboxyl , an ester, an amide, a carbocyclic group, a heterocyclic group, and groups including combinations thereof.

In another approach, the core group is a dendrimer defined as a repeatedly branched molecule (see, e.g., J. M. J. Frechet, D. A. Tomalia, Dendrimers and Other Dendritic Polymers, John Wiley & Sons, Ltd. NY, NY, 2001) and represented in Figure 17.

In this approach, an NHE-binding small molecule is attached via an L to one, several, or optionally all, terminals located on the periphery of the dendrimer. In another approach, the structural element of the dendrimer, called the dendron and illustrated above, is used as the central part, and the NHE-linking group is attached to one, several or, if necessary, all the terminations located on the periphery of the dendron. The number of generations is typically from about 0 to about 6, and preferably from about 0 to about 3. (Generation is defined in, for example, J. M. J. Frechet, D. A. Tomalia, Dendrimers and Other Dendritic Polymers, John Wiley & Sons, Ltd. NY, NY) . Dendrimer and/or dendron structures are known in the art and include, for example, those shown or illustrated in: (i) J. M. J. Frechet, D. A. Tomalia, Dendrimers and Other Dendritic Polymers, John Wiley & Sons, Ltd. NY, NY; (ii) George R Newkome, Charles N. Moorefield and Fritz Vogtle, Dendrimers and Dendrons: Concepts, Syntheses, Applications, VCH Verlagsgesellschaft Mbh; and (iii) Boas, U., Christensen, J.B., Heegaard, P.M.H., Dendrimers in Medicine and Biotechnology: New Molecular Tools, Springer, 2006.

In another approach, the main group may be a polymeric group or an oligomeric group. The polymer or oligomer, in each case, may be considered independently and may include repeat units consisting of a repeat group selected from alkyl (eg, -CH ₂ -), substituted alkyl (eg, -CHR-, in which, for example, R is hydroxy), alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, phenyl, aryl, heterocyclic group, amine, ether, sulfide, disulfide, hydrazine, and any of the above substituted with oxygen, sulfur, sulfonyl, phosphonyl, hydroxyl, alkoxyl, amine , thiol, ether, carbonyl, carboxyl, ester, amide, alkyl, alkenyl, alkynyl, aryl, heterocyclic group, and groups including combinations thereof. In another approach, the core group includes repeat units resulting from the polymerization of ethylene monomers (eg, such as the ethylene monomers listed elsewhere in the description below).

Preferred polymers for polymer groups useful for constructing substantially impermeable or substantially systemically non-bioavailable NHE binding compounds that are polyvalent for use in the various treatments disclosed herein may be prepared by any suitable technique such as free radical polymerization, condensation polymerization, addition polymerization, ring opening polymerization, and/or can be derived from natural polymers such as saccharide polymers. Further, in some embodiments, any of these polymeric groups may be functionalized.

Examples of polysaccharides suitable for use in the preparation of such compounds include, but are not limited to, materials derived from vegetables or animals, including cellulose materials, hemicellulose, alkylcellulose, hydroxyalkylcellulose, carboxymethylcellulose, sulfoethylcellulose, starch, xylan, amylopectin, chondroitin, hyaluronate, heparin , guar, xanthan, mannan, galactomannan, chitin and/or chitosan. More preferred, at least in some cases, are polymeric groups that do not, or do not degrade to a significant extent, under the physiological conditions of the GI tract (such as, for example, carboxymethylcellulose, chitosan, and sulfoethylcellulose).

When free radical polymerization is used, the polymer group can be derived from various classes of monomers including, for example, acrylic, methacrylic, styrenic, vinyl, and diene, typified by the following: styrene, substituted styrene, alkyl acrylate, substituted alkyl acrylate, substituted alkyl methacrylate alkyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, N,N-dialkylacrylamide, N,N-dialkylmethacrylamide, methylbutadiene, butadiene, ethylene, vinyl acetate, and combinations thereof. Functionalized versions of these monomers may also be used, and any of these monomers may be used with other monomers as comonomers. For example, certain monomers or comonomers that may be used in this disclosure include methyl methacrylate, ethyl methacrylate, propyl methacrylate (all isomers), butyl methacrylate (all isomers), 2-ethylhexyl methacrylate, isobromyl methacrylate, methacrylic acid, benzyl methacrylate, phenyl methacrylate, methacrylonitrile, α-methylstyrene, methyl acrylate, ethyl acrylate, propyl acrylate (all isomers), butyl acrylate (all isomers), 2-ethylhexyl acrylate, isobromyl acrylate, acrylic acid, benzyl acrylate, phenyl acrylate, acrylonitrile, styrene, glycidyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate (all isomers), hydroxybutyl methacrylate (all isomers), N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, triethylene glycol methacrylate, itaconic anhydride, itaconic acid, glycidyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate (all isomers), hydroxybutyl acrylate (all isomers), N,N-dimethylaminoethyl acrylate, N,N-diethylaminoethyl acrylate, triethylene glycol acre ylate, methacrylamide, N-methylacrylamide, N,N-dimethylacrylamide, N-tert-butylmethacrylamide, N-n-butylmethacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-tert-butylacrylamide, N-n-butylacrylamide, N-methylacrylamide, N- ethylacrylamide, 4-acryloylmorpholine, vinylbenzoic acid (all isomers), diethylaminostyrene (all isomers), α-methylvinyl benzoic acid (all isomers), diethylamino α-methylstyrene (all isomers), p-vinylbenzene sulfonic acid, p-vinylbenzene sulfonic sodium salt acids, functional alkoxy and alkyl silane monomers, maleic anhydride, N-phenylmaleimide, N-butylmaleimide, butadiene, methyl butadiene, chloroprene, ethylene, vinyl acetate, vinyl formamide, allylamine, vinyl pyridines (all isomers), fluoroacrylate, methacrylates, and combinations thereof. Polymeric units with heteroatoms in the main chain can also be used, including polyethyleneimine and polyethers such as polyethylene oxide and polypropylene oxide, and their copolymers.

In one particular embodiment, the polymer to which the NHE-binding small molecule, NHE, is attached or otherwise forms a part is a polyhydric alcohol (e.g., a polymer having a repeating unit, e.g., a hydroxyl-substituted alkyl such as -CH(OH )-). Polyhydric alcohols, such as mono- and disaccharides, with or without reducing or reducible end groups, may be good candidates, for example, for the installation of an additional functional group, which can make the connection essentially impermeable.

In one particular embodiment, an NHE-binding small molecule, NHE, is attached at one or both ends of the polymer chain. More specifically, in another additional embodiment to the polyvalent embodiment of the present disclosure, a macromolecule (e.g., polymer or oligomer) having one of the following structures can be designed and produced as described here:

I. General Structure of Additional Compound Examples

In one embodiment, the invention relates to a compound having the structure of Formula (I-I):

or a stereoisomer, prodrug or pharmaceutically acceptable salt thereof, wherein: (a) NHE is an NHE-binding small molecule having the following structure of Formula (A-I):

,

,

in which: each R₁, R₂, R₃, R_five and R_nine independently selected from H, halogen, -NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H, C_1-6alkyl, -C_1-6alkyl-OH or a bond linking the NHE-binding small molecule to L, provided that at least one is a bond linking the NHE-binding small molecule to L; R_four selected from H, C₁-C₇ alkyl or a bond linking the NHE-linking small molecule to L; R₆ missing or selected from H and C₁-C₇ alkyl; and Ar1 and Ar2 are independently an aromatic ring or a heteroaromatic ring; (b) Core means the Core having the following structure of Formula (B-I):

,

,

in which: X is chosen from C(X₁), N and N(C_1-6alkyl); X₁selected from hydrogen, optionally substituted alkyl, -NX_aX_b, -NO₂, -NX_c-C(=O)-NX_c-X_a, -C(=O)NX_c-X_a, -NX_c-C(=O)-X_a, -NX_c-SO₂-X_a, -C(=O)-X_a and -OX_a, every X_a and X_b independently selected from hydrogen, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted cycloalkylalkyl, optionally substituted heterocyclyl, optionally substituted heterocyclylalkyl, optionally substituted aryl, optionally substituted aralkyl, optionally substituted heteroaryl and optionally substituted heteroarylalkyl; Y stands for C_1-6alkylene; Z is selected from -NZ_a-C(=O)-NZ_a-, -C(=O)NZ_a-, -NZ_a-C(=O)- and heteroaryl when X is CX₁; Z is selected from -NZ_a-C(=O)-NZ_a-, -NZ_a-C(=O)- and heteroaryl when X is N or N(C_1-6alkyl); and each X_c and Z_aindependently selected from hydrogen and C_1-6alkyl; and (c) L is a bond or linker connecting the Core to NHE-binding small molecules, wherein the resulting NHE-binding compound (i.e., the compound of Formula (I)) has overall physicochemical properties that make it substantially impermeable or essentially systemically non-bioavailable. The core group may be linked to essentially any position on, or within, the NHE-binding small molecule group, provided that its installation does not significantly adversely affect activity.

In another embodiment, the invention relates to a compound having the structure of Formula (II-I):

or a stereoisomer, prodrug or pharmaceutically acceptable salt thereof, wherein: (a) NHE is an NHE-binding small molecule having the structure of Formula (A-I):

,

,

in which: each R₁, R₂, R₃, R_five and R_nine independently selected from H, halogen, -NR₇(CO)R₈, -(CO)NR₇R₈, -SO₂-NR₇R₈, -NR₇SO₂R₈, -NR₇R₈, -OR₇, -SR₇, -O(CO)NR₇R₈, -NR₇(CO)OR₈ and -NR₇SO₂NR₈, where R₇ and R₈ independently selected from H, C_1-6alkyl, -C_1-6alkyl-OH or a bond linking the NHE-binding small molecule to L, provided that at least one is a bond linking the NHE-binding small molecule to L; R_four selected from H, C₁-C₇ alkyl or a bond linking the NHE-linking small molecule to L; R₆ missing or selected from H and C₁-C₇ alkyl; and Ar1 and Ar2 are independently an aromatic ring or a heteroaromatic ring; (b) Core means the core having the following structure of Formula (C-I):

,

,

in which: W is selected from alkylene, polyalkylene glycol, -C(=O)-NH-(alkylene)-NH-C(=O)-, -C(=O)-NH-(polyalkylene glycol)-NH-C(= O)-, -C(=O)-(alkylene)-C(=O)-, -C(=O)-(polyalkylene glycol)-C(=O)- and cycloalkyl; X is N; Y stands for C_1-6alkylene; Z is selected from -NZ_a-C(=O)-NZ_a-, -C(=O)NZ_a-, -NZ_a-C(=O)- and heteroaryl; every Z_a independently selected from hydrogen and C_1-6alkyl; and (c) L is a bond or linker connecting the Central part with NHE-binding small molecules, and the resulting NHE-binding compound (i.e., the compound of Formula (II-I)) has in general physico-chemical properties that make it essentially impermeable or essentially systemically non-bioavailable. The core group may be linked to essentially any position on, or within, the NHE-binding small molecule group, provided that its installation does not significantly adversely affect activity.

It should be noted that in the structures illustrated here, all the various relationships are not shown in every case. For example, in one or more of the structures illustrated above, connections or bonds between the NHE-binding small molecule group and the Main group are not always shown. However, this should not be considered in a limiting sense. Rather, it should be understood that the NHE-binding small molecule is bound or attached in some way (e.g., by a bond or some kind of linker) to the backbone, such that the resulting NHE-binding compound is suitable for use (i.e., substantially impermeable or substantially systemically non-bioavailable in the GI tract).

The above embodiments are further illustrated below. For example, the first presentation of an example of an oligomeric compound below, in which various parts of the compound are identified, provides a broad context for the disclosure herein. It should be noted that while each NHE-binding small molecule in the structure below is the same, it is within the scope of this disclosure that each is independently selected and may be the same or different. In the illustration below, the linker group is a polyethylene glycol (PEG) unit. PEG derivatives are preferred due in part to their water solubility, which can help avoid hydrophobic collapse (an intramolecular interaction of hydrophobic units that can occur when a hydrophobic molecule is exposed to an aqueous environment (see, for example, Wiley, R. A.; Rich, D. H. Medical Research Reviews 1993, 13(3), 327-384) The main group illustrated below is also preferred because it imparts some rigidity to the molecule, allowing the spacing between NHE-binding small molecules to be increased while minimizing the increase in rotational degrees of freedom.

In designing and making substantially impermeable or substantially systemically non-bioavailable NHE binding compounds that can be used for the treatments detailed in this disclosure, it may in some cases be advantageous to first determine the likely site of attachment on the group of the NHE binding small molecule where the central the part or linker can be installed or attached, before creating a set of candidate multivalent or polyvalent compounds. This can be done by one skilled in the art by systematically inserting functional groups or functional groups showing a moiety of the desired core or linker into different group positions of the NHE-binding small molecule and then testing these adducts to determine if the modified compound retains the desired biological properties. (eg inhibition of phosphate transport). Understanding the SAR of a compound also allows the design of cores and/or linkers that positively affect the activity of the resulting compounds.

Another aspect to be considered in the design of the cores and linkers is the limitation or prevention of hydrophobic collapse. Compounds with extended hydrocarbon functional groups can collapse onto themselves in an intramolecular manner, resulting in an increased enthalpy barrier to interaction with the desired biological target. Accordingly, when designing the cores and linkers, they are preferably designed to be resistant to hydrophobic collapse. For example, conformational constraints such as rigid monocyclic, bicyclic, or polycyclic rings can be placed in the core or linker to increase the rigidity of the structure. Unsaturated bonds such as alkenes and alkynes may also or alternatively be installed. Such modifications can make the NHE binding compound available for productive binding to the target. In addition, the hydrophilicity of linkers can be improved by the addition of hydrogen bond donor or acceptor units or ionic units such as amines, which are protonated in the gastrointestinal tract, or acids, which are deprotonated. Such modifications increase the hydrophilicity of the core or linker and help prevent hydrophobic collapse. In addition, such modifications also contribute to the impermeability of the resulting compounds, increasing tPSA.

It should be understood that any embodiment of the compounds of the present invention as set forth above and any particular substituent formulated herein in such compounds as set forth above may be independently combined with other embodiments and/or substituents of such compounds to form embodiments of the inventions, not specifically stated above. In addition, when a list of substituents is given for any particular substituent in a particular embodiment and/or claim, it should be understood that each individual substituent may be excluded from a particular embodiment and/or claim and that the remaining list of substituents will be considered included. within the scope of the invention. In addition, it should be understood that in the present description, combinations of substituents and/or variables of the depicted formulas are only permissible if such combinations result in stable compounds.

III. Essentially systemically bioavailable compounds

A. Physical and performance properties of compounds

Some of the compounds described herein are designed to be substantially active in systemic tissues, including kidney tissues, when administered by any route, including enteral administration. For enteral administration, including oral delivery, some of these compounds are substantially permeable to the epithelium of the gastrointestinal tract, including the epithelium of the mouth, esophagus, stomach, small intestine, and/or large intestine. The term "gastrointestinal lumen" is used here interchangeably with the term "lumen" and refers to a space or cavity within the gastrointestinal tract (GI tract, which may also be referred to as the intestine) delimited by the apical membrane of a patient's gastrointestinal epithelial cells. In some embodiments, the compounds are not absorbed through the epithelial cell layer of the GI tract (also known as the gastrointestinal epithelium). "Gastrointestinal mucosa" refers to the layer(s) of cells that separate the gastrointestinal lumen from the rest of the body and includes the lining of the stomach and intestines, such as the lining of the small intestine. "Gastrointestinal epithelial cell" or "intestinal epithelial cell" as used herein refers to any epithelial cell on the mucosal surface of the gastrointestinal tract facing the lumen of the gastrointestinal tract, including, for example, gastric epithelial cell, intestinal epithelial cell, colonic and colonic epithelial cell intestines, etc.

"Substantially systemically bioavailable" and/or "substantially permeable" within the meaning of the invention (as well as variations of the term) generally includes situations in which a statistically significant amount, and in some embodiments substantially all, of a compound of the present disclosure enters the bloodstream. or systemic tissues via the gastrointestinal lumen. For example, in accordance with one or more embodiments of the present disclosure, preferably at least about 60%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 96%, about 97%, about 98%, about 99%, or even about 99.5%, the compounds enter the bloodstream or systemic tissues through the gastrointestinal lumen. In such cases, localization in the bloodstream or systemic tissues refers to an increase in the net movement of the compound across the epithelial cell layer of the gastrointestinal tract, for example, through both transcellular and paracellular transport, as well as active and/or passive transport. The compound in such embodiments crosses the gastrointestinal epithelial cell layer in a transcellular transport, eg, across the apical membrane of the small intestinal epithelial cell. The compound in these embodiments can also cross "tight junctions" in paracellular transport between gastrointestinal epithelial cells lining the lumen.

In this regard, it should also be noted, however, that in alternative embodiments, "substantially permeable" or "substantially systemically bioavailable" provides, or allows it to occur, some limited delay in the GI tract (e.g., some detectable amount of absorption, such as for example , less than about 0.1%, 0.5%, 1%, or less than about 30%, 20%, 10%, 5%, etc., and the delay range is, for example, from about 1% to 30 % or from 5% to 20%, etc.).

In this regard, it should also be noted that in some embodiments, due to the permeability and/or systemic bioavailability of essentially the compounds of the present invention, no more than about 50%, 60%, 70%, 80%, 90%, or 95% of the compound by of the invention can be recovered from the final feces, for example, within a period of 24, 36, 48, 60, 72, 84 or 96 hours after (eg, enteral) administration to a patient. In some embodiments, less than about 40%, 30%, 20%, or less than about 10%, or less than about 5% of the amount of compound administered is present, or can be recovered from it, in the patient's stool. In this regard, it is to be understood that the recovered compound may include the sum of the parent compound and its metabolites derived from the parent compound, for example, via hydrolysis, conjugation, reduction, oxidation, N-alkylation, glucuronidation, acetylation, methylation, sulfation, phosphorylation, or any another modification that adds atoms to or removes atoms from the parent compound, the metabolites being generated through the action of any enzyme or exposure to any physiological environment, including pH, temperature, pressure, or food interactions, as they exist in the digestive environment.

The measurement of fecal recovery of the compound and metabolites can be carried out using standard methodology. For example, the compound may be administered enterally (e.g., orally) at a suitable dose (e.g., 10 mg/kg) and feces are then collected at predetermined times after dosing (e.g., 24 hours, 36 hours, 48 hours, 60 hours, 72 hours , 96 hours). The parent compound and metabolites can be extracted with an organic solvent and analyzed quantitatively using mass spectrometry. Analysis of the mass balance of the parent compound and metabolites (including, parent = M, metabolite 1 [M+16] and metabolite 2 [M+32]) can be used to determine the percentage of recovery in the feces.

(i) C _max and IC ₅₀

In some embodiments, the substantially systemically bioavailable compounds detailed herein, when administered alone or in combination with one or more additional pharmaceutically active compounds or agents to a patient, exhibit a maximum concentration detectable in serum, defined as C_max, which is approximately the same or greater than the inhibitory concentration IC₅₀ compounds in relation to the transport or capture of phosphate ions (Pi). In some embodiments, for example, C_max is about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 200%, 300%, 400%, 500 % or more than IC₅₀ to inhibit Pi transport or uptake. In some embodiments, about 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100X (100 times) IC₅₀ regarding inhibition of Pi transport or uptake.

Additionally, or alternatively, it should also be noted that, in various embodiments of the present disclosure, one or more of the compounds detailed herein, when administered to a patient, may have a C_max:IC₅₀ (with respect to inhibition of Pi transport or uptake) in which C_max and IC₅₀ expressed in terms of the same units, in about or at least about 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50 , 60, 70, 80, 90, or 100, or in the range of about 1-100, 1-50, or 1-10.

Additionally, or alternatively, it should also be noted that, in various embodiments of the present disclosure, one or more of the compounds detailed herein, when administered (e.g., enterally) alone or in combination with one or more additional pharmaceutically active compounds or agents to a patient, may have C_max about or greater than about 10 ng/ml, about 12.5 ng/ml, about 15 ng/ml, about 17.5 ng/ml, about 20 ng/ml, about 30 ng/ml, about 40 ng/ml, about 50 ng/ml, about 60 ng/ml, about 70 ng/ml, about 80 ng/ml, about 90 ng/ml, about 100 ng/ml, or about 200 ng/ml, with C_max is, for example, within the range of from about 10 ng/ml to about 200 ng/ml, from 10 ng/ml to about 100 ng/ml, or from about 10 ng/ml to about 50 ng/ml.

B. Examples of Substantially Systemically Bioavailable Compounds

In general, the present disclosure encompasses essentially any small molecule, which may be monovalent or polyvalent, that binds to, interacts with, and/or modulates NHE3, and has activity as a phosphate transport inhibitor, including small molecules that are substantially permeable or substantially systemic. bioavailable when administered via the gastrointestinal tract or otherwise, and including known NHE binding and NHE inhibitory compounds. Some embodiments thus include compounds that are generally represented by the group "NHE" as described elsewhere in the description (eg, above), wherein NHE is an NHE-binding small molecule.

Small molecules suitable for use (ie, suitable for use as substantially bioavailable compounds) include those illustrated below.

In view of the foregoing, in one particular embodiment, the following small molecule disclosed in US Patent Application 2005/0054705, the entire contents of which (and in particular the text of pages 1-2) are incorporated herein by reference for all relevant and related purposes, may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference. In one particularly preferred embodiment, R₆ and R₇ denote a halogen (e.g. Cl), R_five stands for lower alkyl (for example, CH₃), and R₁-R_four denotes H, and the compound has, for example, the structure:

In another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 1-2) are incorporated herein in all relevant and related purposes may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular page 49) are incorporated herein in all relevant and related purposes, may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 118-120 and 175-177) are incorporated herein description, for all relevant and related purposes, may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 129-131) are incorporated herein in all relevant and related purposes may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference. (In this regard, it should be noted that the Z substituent within the structure illustrated above should not be confused with the Z group, which, in accordance with the present disclosure, can be attached to an NHE-binding small molecule to effectively make the resulting "NHE -Z" essentially impenetrable).

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 127-129) are incorporated herein in all relevant and related purposes may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference. (In this regard, it should be noted that the Z within the ring of the structure illustrated above should not be confused with the Z group, which, according to the present disclosure, can be attached to an NHE-binding small molecule to effectively make the resulting "NHE -Z" essentially impenetrable).

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 134-137) are incorporated herein in all relevant and related purposes may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 31-32 and 137-139) are incorporated herein description, for all relevant and related purposes, may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 37-45) are incorporated herein in all relevant and related purposes may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference. (In this regard, it should be noted that the Z within the ring structure illustrated above should not be confused with the Z group, which, according to the present disclosure, can be attached to an NHE-binding small molecule to effectively make the resulting "NHE -Z" essentially impenetrable).

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 100-102) are incorporated herein in all relevant and related purposes may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference (in which, in particular, wavy bonds indicate a variable length or a variable number of atoms).

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 90-91) are incorporated herein in all relevant and related purposes may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in US Pat. and related purposes may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in these structures are defined in the cited patents, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 35-47) are incorporated herein in all relevant and related purposes may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 154-155) are incorporated herein in all relevant and related purposes, may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 132-133) are incorporated herein in all relevant and related purposes may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particular embodiment, the following small molecule disclosed in Canadian Patent Application 2,241,531 (or International Patent Publication WO97/24113), the entire contents of which (and in particular pages 58-65 and 141-148) are incorporated herein description, for all relevant and related purposes, may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patent application, the details of which are incorporated herein by reference. (In this regard, it should be noted that the Z within the ring structure illustrated above should not be confused with the Z group, which, according to the present disclosure, can be attached to an NHE-binding small molecule to effectively make the resulting "NHE -Z" essentially impenetrable).

In yet another particular embodiment, the following small molecule disclosed in US Pat. 405) incorporated herein by reference for all relevant and related purposes may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables in this structure are defined in the cited patents, the details of which are incorporated herein by reference. A particularly preferred small molecule falling under the above structure is further illustrated below (see, for example, Example 1 of patent 6,911,453, the entire contents of which are specifically incorporated herein by reference):

In yet another particular embodiment, the following small molecules disclosed in US Patent Publications 2004/0039001, 2004/0224965, 2005/0113396 and 2005/0020612, all of which are incorporated herein by reference for all relevant and related purposes, may be suitable for use as essentially systemically bioavailable NHE binders).

The variables in these structures are defined above and/or in one or more of the cited patent applications, the details of which are incorporated herein by reference, and/or as illustrated above (with broken links indicating the point of attachment for the Y group to the fused heterocyclic ring). In particular, in various embodiments, the combination of X and Y may be as follows:

In a particularly preferred embodiment of the above structure, the small molecule has the general structure:

,

,

in which R₁, R₂ and R₃ may be the same or different, but preferably are different and are independently selected from H, NR'R'' (where R' and R'' are independently selected from H and a hydrocarbyl such as lower alkyl as defined elsewhere) and structures :

In a more preferred embodiment of the above structure, a small molecule falling under the above structure is further illustrated below (see, for example, the compound on page 5 of patent application 2005/0020612, the entire contents of which are specifically incorporated herein by reference) :

In another particularly preferred embodiment, the following small molecule disclosed in US Pat. essentially a systemically bioavailable NHE binding compound.

In this structure, R may preferably be selected from H and (CH ₃ ) ₂ NCH ₂ CH ₂ - with H being particularly preferred in various embodiments.

In yet another particular embodiment, the following small molecule as disclosed in US Pat. No. 6,005,010 (and in particular columns 1-3) and/or US Pat. incorporated herein by reference for all relevant and related purposes, may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variable (“R”) in this structure is defined in the cited patent application, the details of which are incorporated herein by reference.

In another embodiment, NHE-binding small molecules suitable for use as essentially systemically bioavailable compounds are disclosed in WO2010/025856, the entire content of which is incorporated herein by reference for all relevant and related purposes, and has the following structure.

The variables in this structure are defined in WO2010/025856, the details of which are incorporated herein by reference.

In another particularly preferred embodiment, the following small molecule disclosed in US Patent Application 2008/0194621, the entire content of which (and in particular the text of Example 1) is incorporated herein by reference for all relevant and related purposes, may be suitable for use as a substantially systemically bioavailable NHE binding compound.

The variables ("R ₁ ", "R ₂ and "R ₃ ") in this structure are as defined above and/or as defined in the cited patent application, the details of which are incorporated herein by reference.

In yet another particularly preferred embodiment, the following small molecule disclosed in US Patent Application 2007/0225323, the entire content of which (and in particular the text of Example 36) is incorporated herein by reference for all relevant and related purposes, may be suitable for use as a substantially systemically bioavailable NHE binding compound.

In another particularly preferred embodiment, the following small molecule disclosed in US Pat. No. 6,911,453, the entire contents of which (and in particular the text of Example 35) are incorporated herein by reference for all relevant and related purposes, may be suitable for use as a substantially systemically bioavailable NHE binding compound.

In one particularly preferred embodiment of the present disclosure, the small molecule may be selected from the group consisting of:

In some embodiments, the substantially systemically bioavailable NHE binding and/or modulating compound is selected from one or more of the following:

IV. Pharmaceutical compositions and methods of treatment

For purposes of administration, the compounds of the present invention may be administered to a patient or person in the form of a crude chemical compound, or may be formulated in the form of pharmaceutical compositions. Pharmaceutical compositions of the present invention typically include a compound of the invention and a pharmaceutically acceptable carrier, diluent or excipient. The compound is present in the composition in an amount that is effective for treating the particular disease or condition of interest, as described herein, and preferably with acceptable toxicity to the patient. The activity of the compound(s) can be determined by a person skilled in the art, for example, as described below in the Examples. Suitable concentrations and dosages can be readily determined by those skilled in the art.

A compound or composition of the invention may be used in a method of treating essentially any disease or other condition in a patient that would benefit from inhibition of phosphate uptake in the gastrointestinal tract and/or kidneys.

For example, for purposes of explanation, and not limitation, kidney damage reduces the production and activity of renal 1-alpha hydroxylase, resulting in a decrease in 1,25-dihydroxy vitamin D. Decreased levels of vitamin D limit gastrointestinal absorption of calcium, resulting in decreased serum calcium levels. . The combination of lower 1,25-dihydroxy vitamin D and lower serum calcium levels synergistically stimulates parathyroid tissue to produce and secrete PTH. Loss of nephrons also impairs Pi excretion, but serum P levels are actively protected by the actions of PTH and FGF-23 and higher serum P levels, which greatly enhance excretion. PO_fourwith urine. However, the actions of PTH and FGF-23 in tubules cannot maintain serum P levels in the face of continuous loss of nephrons. As renal failure progresses to a loss of approximately 40-50% of renal function, the decrease in the amount of functioning renal tissue does not provide for the excretion of the full amount of ingested phosphate needed to maintain homeostasis. As a result, hyperphosphatemia develops. In addition, elevated serum P levels interfere with renal 1-alpha hydroxylase activity, further suppressing activated vitamin D levels and further stimulating PTH, leading to secondary hyperparathyroidism (sHPTH).

Phosphorus imbalance, however, does not necessarily equate to hyperphosphatemia. Rather, the vast majority of CKD patients who are not yet on dialysis show normophosphatemia, but their phosphorus is positive, with excess phosphorus located in the vasculature in the form of ectopic calcification, eg, intima-localized vascular calcification. Clinically, CKD patients have elevated levels of FGF-23, which are strongly associated with deterioration in renal function and with reduced levels of calcitriol, and it has been hypothesized that FGF-23 synthesis is induced by the presence of excess P in the body due to kidney failure.

In addition, an unrecognized effect on cardiovascular disease is postprandial phosphatemia, that is, a deviation in serum P secondary to food intake. Further, the acute effect of phosphorus loading on endothelial function in vitro and in vivo was investigated. Exposure of bovine aortic endothelial cells to phosphorus increases the production of reactive oxygen species and reduces nitric oxide, a known vasodilator. In the acute P loading study in healthy volunteers described above, flow-mediated dilation was found to be inversely correlated with postprandial serum P (Shuto et al., 2009b, J. Am. Soc. Nephrol, v. 20, no. 7, pp. 1504-1512).

Accordingly, in some embodiments, a compound or composition of the invention may be used in a method selected from one or more of the following: a method of treating hyperphosphatemia, if needed postprandial hyperphosphatemia; a method for treating a kidney disease (eg, chronic kidney disease (CKD), end stage renal disease (ESRD)); a method for reducing serum creatinine levels; a method for treating proteinuria; a method for delaying the start of renal replacement therapy (RRT), such as dialysis; a method for reducing FGF23 levels; a method for reducing the hyperphosphatemic effect of active vitamin D; a method of alleviating hyperparathyroidism such as secondary hyperparathyroidism; a method for reducing serum parathyroid hormone (PTH or iPTH); a method for reducing weight gain in the interdialysis period (IDWG); a method for improving endothelial dysfunction, if necessary, caused by postprandial serum phosphate; a method of reducing vascular calcification or alleviating intima-located vascular calcification; a method for reducing urinary phosphorus (eg, enteral administration of a GI-active, essentially systemically non-bioavailable compound); a method of increasing urinary phosphorus (eg, by administering a substantially systemically bioavailable compound, by administering a substantially systemically non-bioavailable compound by a route other than enteral administration); a method for normalizing serum phosphorus levels; a method for reducing phosphate load in an elderly patient; a method for reducing dietary phosphate uptake; a method for reducing postprandial calcium absorption; a method for reducing renal hypertrophy; a method for reducing cardiac hypertrophy; and a method for treating obstructive sleep apnea.

In some embodiments, implementation, the invention relates to the use of compounds or compositions for the treatment of hyperphosphatemia, in case of need for postprandial hyperphosphatemia; treatment of a kidney disease (eg, chronic kidney disease (CKD), end stage renal disease (ESRD)); decrease in serum creatinine levels; treatment of proteinuria; delays in starting renal replacement therapy (RRT) such as dialysis; decrease in FGF23 levels; reducing the hyperphosphatemic effect of active vitamin D; relief of hyperparathyroidism such as secondary hyperparathyroidism; decrease in serum parathyroid hormone (PTH or iPTH); reducing the increase in body weight in the interdialysis period (IDWG); improvement of endothelial dysfunction, if necessary, caused by postprandial serum phosphate; reducing vascular calcification or alleviating intima-located vascular calcification; reduction of urinary phosphorus (eg, by enteral administration of a GI-active, essentially systemically non-bioavailable compound); increasing urinary phosphorus (eg, by administering a substantially systemically bioavailable compound, by administering a substantially systemically non-bioavailable compound via a route other than enteral administration); normalization of serum levels of phosphorus; reduction of phosphate load in an elderly patient; reduced dietary phosphate uptake; decrease in postprandial absorption of calcium; reduction of renal hypertrophy; reduction of cardiac hypertrophy; and treatment of obstructive sleep apnea.

In some embodiments, the invention relates to the use of a compound or composition in the preparation of a medicament for: the treatment of hyperphosphatemia, if necessary, postprandial hyperphosphatemia; treatment of a kidney disease (eg, chronic kidney disease (CKD), end stage renal disease (ESRD)); decrease in serum creatinine levels; treatment of proteinuria; delays in starting renal replacement therapy (RRT) such as dialysis; decrease in FGF23 levels; reducing the hyperphosphatemic effect of active vitamin D; relief of hyperparathyroidism such as secondary hyperparathyroidism; decrease in serum parathyroid hormone (PTH or iPTH); reducing the increase in body weight in the interdialysis period (IDWG); improvement of endothelial dysfunction, if necessary, caused by postprandial serum phosphate; reduction of vascular calcification or relief of intima-located vascular calcification; reduction of urinary phosphorus (eg, by enteral administration of a GI-active, essentially systemically non-bioavailable compound); increasing urinary phosphorus (eg, by administering a substantially systemically bioavailable compound, by administering a substantially systemically non-bioavailable compound via a route other than enteral administration); normalization of serum levels of phosphorus; reduction of phosphate load in an elderly patient; reduced dietary phosphate uptake; decrease in postprandial absorption of calcium; reduction of renal hypertrophy; reduction of cardiac hypertrophy; and treatment of obstructive sleep apnea.

In some embodiments, the invention relates to a pharmaceutical composition comprising a compound or composition for: treating hyperphosphatemia, if necessary, postprandial hyperphosphatemia; treatment of a kidney disease (eg, chronic kidney disease (CKD), end stage renal disease (ESRD)); decrease in serum creatinine levels; treatment of proteinuria; delays in starting renal replacement therapy (RRT) such as dialysis; decrease in FGF23 levels; reducing the hyperphosphatemic effect of active vitamin D; relief of hyperparathyroidism such as secondary hyperparathyroidism; decrease in serum parathyroid hormone (PTH or iPTH); reducing the increase in body weight in the interdialysis period (IDWG); improvement of endothelial dysfunction, if necessary, caused by postprandial serum phosphate; reduction of vascular calcification or relief of intima-located vascular calcification; reduction of urinary phosphorus (eg, by enteral administration of a GI-active, essentially systemically non-bioavailable compound); increasing urinary phosphorus (eg, by administering a substantially systemically bioavailable compound, by administering a substantially systemically non-bioavailable compound via a route other than enteral administration); normalization of serum levels of phosphorus; reduction of phosphate load in an elderly patient; reduced dietary phosphate uptake; decrease in postprandial absorption of calcium; reduction of renal hypertrophy; reduction of cardiac hypertrophy; and treatment of obstructive sleep apnea.

Hyperphosphatemia refers to a condition in which there is an elevated level of phosphate in the blood. The average serum mass of phosphorus in an adult is usually about 2.5-4.5 mg/dl (about 0.81-1.45 mmol/l). Levels are often about 50% higher in infants and about 30% higher in children due to the effects of growth hormone. Therefore, some methods include treating an adult human having hyperphosphatemia, wherein the patient has a serum phosphorus mass of about or at least about 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5, 1, 5.2, 5.3, 5.4, or 5.5 mg/dl. In some aspects, treatment reduces serum concentrations or levels of phosphate in a patient suffering from hyperphosphatemia to about 150%, 145%, 140%, 135%, 130%, 125%, 120%, 115%, 110%, 105%, or 100 % (normalized) normal serum phosphate levels (eg, 2.5-4.5 mg/dL or 0.81-1.45 mmol/L for an adult). In some aspects, the treatment regimen results in and/or includes monitoring phosphate levels so that they remain within the range of about 2.5-4.5 mg/dL (about 0.81-1.45 mmol/L). The invention also includes methods of treating a child or adolescent wherein the patient has a serum phosphorus mass of about or at least about 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6 .7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9 or 8.0 mg/dl. As noted herein, in these and related embodiments, administration of a compound or composition described herein can reduce a patient's serum phosphorus mass by about or at least about 5%, 10%, 20%, 30%, 40%, 50 %, 60%, 70%, 80%, 90%, 100%, 200% or more.

Some embodiments relate to methods of treating chronic kidney disease (CKD), a condition characterized by progressive loss of kidney function. Common causes of CKD include diabetes mellitus, hypertension, and glomerulonephritis. Therefore, some methods include the treatment of a patient with CKD, where the patient, if necessary, also has one or more of the above conditions.

In some aspects, a patient is classified as having CKD if they have a glomerular filtration rate (GFR) of less than 60 ml/min/1.73 m ² for about 3 months, whether or not they also have kidney damage. Some methods thus include treating a patient with a GFR (eg, initial GFR prior to treatment) of about or less than about 60, 55, 50, 45, 40, 30, 35, 20, 25, 20, 15, or 10 ml/ min/1.73 ^m2 or so. In some embodiments, administration of a compound or composition described herein may result in an increase in GFR of about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80 %, 90%, 100%, 200% or more.

CKD is most commonly characterized according to the stage of the disease: Stage 1, Stage 2, Stage 3, Stage 4, and Stage 5. Stage 1 CKD includes patients with kidney damage and a normal or relatively high GFR of approximately or greater than approximately 90 ml/min/1, 73 ^m2 . Stage 2 CKD includes patients with kidney damage and a GFR of approximately 60-89 ml/min/1.73 m ² . Stage 3 CKD includes patients with kidney damage and a GFR of approximately 30-59 ml/min/1.73 m ² . Stage 4 CKD includes patients with kidney damage and a GFR of approximately 15-29 ml/min/1.73 m ² . Stage 5 CKD includes patients with established kidney failure and a GFR of less than about 15 ml/min/1.73 m ² . Stage 5 CKD is also referred to as end stage renal disease (ESRD). Accordingly, in some methods, the patient has Stage 1, 2, 3, 4, or 5 CKD and one or more of its associated clinical characteristics (eg, defined GFR, kidney damage). In some embodiments, the patient has ESRD and one or more of its associated clinical characteristics, as described herein and known in the art.

CKD can be characterized according to the affected parts of the kidney. For example, in some aspects, CKD includes vascular-associated CKD, including large vessel disease, such as bilateral renal artery stenosis, and small vessel disease, such as ischemic nephropathy, hemolytic-uremic syndrome, and vasculitis. In some aspects, CKD includes glomerular-associated CKD, including primary glomerular disease such as central segmental glomerulosclerosis and IgA nephritis, and secondary glomerular diseases such as diabetic nephropathy and lupus nephritis. The invention also includes tubulointerstitial-associated CKD, including polycystic kidney disease, drug and toxin-induced chronic tubulointerstitial nephritis, and reflux nephropathy. Some patients treated for CKD may thus have one or more of the above CKD-associated characteristics.

Some aspects relate to methods of treating a patient with kidney injury or one or more symptoms/clinical signs of kidney injury. Examples of kidney damage (eg, CKD-related kidney injury) and its associated symptoms include pathological abnormalities and markers of damage, including abnormalities identified in blood testing (eg, high blood or serum creatinine levels, creatinine clearance), urine testing (eg, proteinuria ) and/or imaging studies.

Creatinine is a breakdown product of creatine phosphate in muscle and is an easily measurable and useful indicator of kidney health. The normal reference range for humans is for blood or serum creatinine ranges of about 0.5 to 1.0 mg/dl (about 45-90 µmol/l) for women and about 0.7 to 1.2 mg/dl (about 60-110 µmol/l) for men. Therefore, some patients treated according to the methods described herein (eg, initially, prior to treatment) may have blood or serum creatine levels that are about or greater than about 1.0, 1.1, 1.2, 1.3 , 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 mg/dl. In these and related embodiments, administration of a compound or composition described herein can decrease total blood or serum creatinine levels in a patient by about or at least about 5%, 10%, 20%, 30%, 40%, 50% , 60%, 70%, 80%, 90%, 100% or 200% or more.

Creatinine clearance rate (C_Cr or CrCl) refers to the volume of blood plasma that is released from creatinine per unit time; it is measured by comparing blood and urine creatinine levels over time (eg, 24 hours). Creatine clearance is often measured as milliliters/minute (ml/min) or as a function of body weight (ml/minute/kg). Depending on the test being performed, normal values are approximately 97-137 ml/min for men and approximately 88-128 ml/min for women. Decreased creatinine clearance provides a useful indication of kidney damage. Therefore, some male patients treated according to the methods described here (eg, initially, before treatment) may have C_Cr about or less than about 97, 96, 95, 94, 93, 92, 91, 90, 89, 88, 87, 86, 85, 84, 83, 82, 81, 80, 79, 78, 77, 76, 75 , 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50 or less. Some female patients for treatment according to the methods described here (for example, initially, before treatment) may have C_Cr about or less than about 88, 87, 86, 85, 84, 83, 82, 81, 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66 , 65, 64, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 47, 46, 45, 44, 43, 42, 41, 40 or less. In some embodiments, administration of a compound or composition described herein may maintain or increase C_Cr in a patient by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% or 200% or more.

Proteinuria refers to the condition of excess protein in the urine. It is associated with various disease states, including kidney damage. Proteinuria is often characterized as a urinary protein/creatinine ratio greater than about 45 mg/mmol, or, in some tests, an albumin/creatine ratio greater than about 30 mg/mmol. Some patients treated according to the methods of the invention (e.g., prior to treatment) have proteinuria, alone or in combination with CKD or other kidney injury, including patients with urinary protein/creatinine ratios of about or greater than about 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, or 120 mg/mmol and/or urinary albumin/creatinine ratio of about or greater than about 30, 35, 40, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115 or 120 mg/mmol. In these and related embodiments, administration of a compound or composition described herein may result in the treatment of proteinuria, e.g., by reducing the urinary protein/creatinine ratio and/or the urinary albumin/creatinine ratio by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% or 200% or more.

CKD is associated with various clinical symptoms. Examples include high blood pressure (hypertension), urinary accumulation, hyperkalemia, anemia, hyperphosphatemia, hypocalcemia, metabolic acidosis, and atherosclerosis. Thus, in some methods, a CKD patient may also have or be at risk for one or more of the above clinical symptoms. In some aspects, a patient with CKD has or is at risk of having hyperphosphatemia, as described here.

Renal replacement therapy (RRT) refers to various life-sustaining treatments for kidney failure, including those initiated at later stages of CKD and ESRD. Examples of RRT include dialysis, hemodialysis, hemofiltration, and kidney transplant. In some embodiments, a patient for treatment according to the methods of the invention will be, is being, or has been, one or more types of RRT. In some embodiments, the patient has not yet undergone RRT and administration of a compound described herein delays the time of RRT initiation (e.g., relative to the untreated state) by about or at least about 1, 2, 3, 4, 5, 6, 7 , 8, 9, 10, 11, 12 weeks, or about or at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 months, or about or at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 years or more.

Fibroblast growth factor 23 (FGF23) regulates the metabolism of vitamin D and phosphorus. It also promotes phosphaturia and reduces the production of calcitriol. Increased levels of FGF23 are associated with mortality, left ventricular hypertrophy (or left ventricular mass index), myocardial working index, endothelial dysfunction, and progression of CKD. Indeed, FGF23 levels increase progressively in the early stages of CKD, presumably as a physiological adaptation to maintain normal serum phosphate levels or normal phosphorus balance. FGF23 levels may also directly contribute to tissue damage in the heart, blood vessels, and kidneys. Some embodiments thus relate to the treatment of patients having elevated blood or serum levels of FGF23 (see, for example, Kirkpantur et al., Nephrol Dial Transplant. 26: 1346-54, 2011), including CKD patients and patients tolerating dialysis/hemodialysis. In some aspects, administration of a compound or composition described herein reduces the log blood or serum levels of FGF23 by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70 %, 80%, 90%, 100% or 200% or more.

Vitamin D stimulates, among other things, the absorption of phosphate ions in the small intestine. Consequently, excess levels or activity of Vitamin D can lead to increased phosphate levels and hyperphosphatemia. Some embodiments thus relate to methods of reducing the hyperphosphatemic effect of active vitamin D, for example, in a patient having elevated levels or activity of Vitamin D. In some aspects, the patient has Vitamin D toxicity due to excess intake of Vitamin D.

Hyperparathyroidism is a disorder in which the parathyroid glands produce too much parathyroid hormone (PTH). Secondary hyperparathyroidism is characterized by excessive secretion of PTH in response to hypocalcemia and associated parathyroid hypertrophy. CKD is the most common cause of secondary hyperparathyroidism, generally because the kidneys are unable to convert enough vitamin D to its active form and excrete enough phosphate. Insoluble calcium phosphate is formed in the body and thus removes calcium from the circulation, leading to hypocalcemia. The parathyroid glands then further increase PTH secretion in an attempt to increase serum calcium levels. Some patients for treatment according to the methods described herein may thus exhibit (eg, initially, prior to treatment) hyperparathyroidism and/or elevated PTH levels, optionally in combination with CKD, hyperphosphatemia, hypocalcemia, or other condition or symptom described here. In some aspects, administration of a compound or composition described herein can reduce hyperparathyroidism, including secondary hyperparathyroidism, in a patient. In some aspects, administration of a compound or composition described herein can reduce PTH levels by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% , 90%, 100%, or 200% or more, for example, by decreasing serum phosphate levels and the associated formation of insoluble calcium phosphate, increasing available calcium, and thus decreasing hypocalcemia-induced PTH production.

In some embodiments, administration of a compound described herein, for example, a dual activity compound that inhibits both Pi transport and NHE3-mediated sodium and hydrogen ion antiport, may provide multiple therapeutic effects in a CKD patient. In some cases, administration of a dual activity compound reduces the logarithm of FGF23 levels and serum parathyroid hormone (PTH) levels by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70 %, 80%, 90%, 100% or 200% or more relative to the untreated state, reduces blood pressure and reduces proteinuria by at least about 5%, 10%, 20%, 30%, 40%, 50%, 60% , 70%, 80%, 90%, 100%, or 200% or more relative to the raw state.

In particular embodiments, administration of a compound described herein, e.g., a dual activity compound that inhibits both Pi transport and NHE3-mediated sodium and hydrogen ion antiport, may provide multiple therapeutic effects in a patient with ESRD (or Stage 5 CKD) . In some cases, administration of a dual activity compound reduces serum concentrations or phosphate levels by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or 200% or more relative to the untreated state and reduces interdialysis body weight gain (IDWG) by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or 200% or more of the raw state. IDWG is an easily measurable parameter that is usually assessed before, during or after dialysis (see Sarkar et al., Semin Dial. 19:429-33, 2006).

Hyperphosphatemia can lead to endothelial dysfunction in both healthy individuals and patients with renal disease, regardless of vascular calcification (see, for example, Di Marco et al., Kidney International. 83:213-222, 2013). Management of serum phosphate levels in accordance with dietary phosphate or phosphate binder restriction may prevent the development of cardiovascular disease in these patients. Studies have also shown that dietary phosphate restriction can improve aortic endothelial dysfunction (eg, in CKD with hyperphosphatemia) by increasing endothelial nitric oxide synthase and Akt activating phosphorylation (see, for example, Van et al., J Clin Biochem Nutr. 51:27 -32, 2012). Some patients for treatment according to the methods described here may have or be at risk of getting endothelial dysfunction, possibly associated with hyperphosphatemia, renal disease, or any other condition described here. By reducing postprandial or dietary phosphate uptake, alone or in combination with dietary phosphate restriction, administration of a compound or composition described herein may reduce the risk of developing endothelial dysfunction or may improve pre-existing endothelial dysfunction, including endothelial dysfunction caused by postprandial serum phosphate.

Hyperphosphatemia is the primary inducer of vascular calcification (see Giachelli, Kidney Int. 75:890-897, 2009). The deposition of calcium phosphate, mainly in the form of apatite, is a marker of vascular calcification and can occur in blood vessels, myocardium, and heart valves. Together with the passive deposition of calcium phosphate in extraskeletal tissues, inorganic phosphate can also cause arterial calcification directly through the "ossification" of the tunica media in the vasculature. In addition, vascular smooth muscle cells respond to elevated phosphate levels by mediating the osteochondrogenic phenotype change and mineralization of their extracellular matrix through a mechanism requiring sodium-dependent phosphate co-transporters.

Intimal calcification is usually found in atherosclerotic lesions. Medial calcification is commonly seen in age-related arteriosclerosis and diabetes and is the main form of calcification seen in ESRD. Indeed, extensive arterial wall and soft tissue calcification is a common finding in CKD patients, including those with ESRD. In valves, calcification is the hallmark of aortic valve stenosis and occurs in both leaflets and annulus, predominantly in areas of inflammation and mechanical stress. These mechanical changes are associated with increased arterial pulse wave velocity and pulse amplitude and result in impaired arterial compliance, increased afterload promoting left ventricular hypertrophy and impairing coronary perfusion (see Guerin et al., Circulation. 103:987-992, 2001). Both intimal and medial calcifications may thus contribute to the morbidity and mortality associated with cardiovascular disease and are likely to be major components of the significant increase in the risk of cardiovascular mortality observed in patients with CKD and ESRD. Serum phosphate control may thus reduce the formation of calcium/phosphate products, and thus reduce vascular calcification. Accordingly, some patients for treatment according to the methods of the invention may have or be at risk of developing vascular calcification, including intimal and/or medial calcification, possibly combined with any of the conditions of hyperphosphatemia, CKD, and ESRD. In some embodiments, administration of a compound or composition described herein reduces the risk of developing or reduces the formation or levels of vascular calcification in a patient. In particular embodiments, administration of a compound or composition described herein can reduce vascular calcification by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80 %, 90%, 100%, or 200% or more, for example, relative to the raw state.

Elderly patients may be particularly susceptible to elevated phosphate levels. For example, dietary and genetic studies provide in vivo evidence that phosphate toxicity accelerates the aging process and suggest a novel role for phosphate in mammalian aging (see, for example, Ohnishi and Razzaque, FASEB J. 24:3562-71, 2010). These studies show that excess phosphate is associated with many symptoms of premature aging, including kyphosis, uncoordinated movement, hypogonadism, infertility, skeletal muscle wasting, emphysema, and impaired osteogenesis, as well as generalized atrophy of the skin, gut, thymus, and spleen. Some embodiments thus relate to attenuating the phosphate load in an elderly patient, for example by reducing one or more symptoms of premature aging, comprising administering to an elderly patient a compound described herein. In some cases, the elderly patient is about or at least about 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100 years or more.

Hypertrophy refers to an increase in the volume of an organ or tissue due to an increase in its constituent cells. Hyperphosphatemia is associated with myocardial hypertrophy, including left ventricular hypertrophy (see Neves et al., Kidney Int. 66:2237-44, 2004; and Achinger and Ayus, Am Soc Nephrol. 17(12 Suppl 3):S255-61, 2006) , and compensatory renal hypertrophy, including glomerular hypertrophy, the latter often seen in CKD. Some patients for treatment according to the methods of the invention may have (eg, initially, prior to treatment) myocardial hypertrophy, renal hypertrophy, or both, alone or in combination with CKD or kidney injury. In some embodiments, administration of a compound described herein can reduce myocardial hypertrophy and/or renal hypertrophy by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70 %, 80%, 90%, 100%, 200% or more relative to the raw state.

Sleep apnea is a sleep disorder characterized by abnormal pauses in breathing or abnormally slow breathing during sleep. Pauses in breathing are referred to as apneas, and low-breathing events are referred to as abrupt decreases in the rate and depth of breathing. These events may last from seconds to minutes and may occur many times per hour (eg, ≥ 30 times per hour). The Apnea-Hypopnea Index (AHI) is calculated as the total number of apneas or hypopneas divided by hours of sleep. Mild, moderate, and severe sleep apnea are defined as AHI 5-14, 15-29, and ≥ 30 events/hour, respectively. Obstructive sleep apnea (OSA) is the most common type of sleep apnea. In OSA, breathing is difficult due to the collapse of the soft tissue walls in the airways, which occurs because the muscle tone of the body is usually weakened during sleep. Chronic severe OSA can lead to hypoacidity (low blood oxygen), sleep deprivation, and other complications, including cardiovascular complications. In addition, a high prevalence of CKD is present in patients with severe OSA, including those without hypertension or diabetes. Strongly positive correlations have also been found between OSA severity and functional kidney injury (see Chou et al., Nephrol. Dial. Transplant. 0:1-6, 2011). In addition, acute hypoxia is associated with proteinuria, a sign of kidney damage or dysfunction (see Luks et al., J Am Soc Nephrol. 19:2262-2271, 2008). OSA and hypoxia are thus associated with renal dysfunction, and OSA is considered an autonomous risk factor for CKD (Chou et al., supra). Accordingly, some patients for treatment according to the methods of the invention may have OSA, alone or in combination with CKD or other symptoms of kidney damage. Administration of a compound or composition described herein to a patient with OSA can reduce AHI by about or at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or more .

The administration of the compounds of the invention, or their pharmaceutically acceptable salts, in pure form or in a suitable pharmaceutical composition, may be carried out by any of the accepted methods of administering such agents. Pharmaceutical compositions of the invention may be prepared by combining a compound of the invention with a suitable pharmaceutically acceptable carrier, diluent or excipient and may be formulated into solid, semi-solid, liquid or gaseous forms such as tablets, capsules, powders, granules, ointments, solutions , suppositories, injections, inhalants, gels, microspheres and aerosols. Typical routes of administration of such pharmaceutical compositions include, without limitation, oral, topical, transdermal, inhalation, parenteral, sublingual, buccal, rectal, vaginal, and intranasal. The term parenteral within the scope of the invention includes subcutaneous injection, intravenous, intramuscular, epigastric injection or infusion. The pharmaceutical compositions of the invention are formulated to make the active ingredients contained therein bioavailable upon administration of the composition to a patient. Compositions administered to a person or patient take the form of one or more dosage units, where, for example, a tablet may be a single dosage unit and an aerosol container of a compound of the invention may contain multiple dosage units. The actual methods of obtaining such dosage forms are known or will be obvious to a specialist; for example, see Remington: The Science and Practice of Pharmacy, 20th Edition (Philadelphia College of Pharmacy and Science, 2000). The composition to be administered, in any case, contains a therapeutically effective amount of a compound of the invention, or a pharmaceutically acceptable salt thereof, for the treatment of a disease or condition in accordance with the disclosure of this invention.

The pharmaceutical composition of the invention may be in solid or liquid form. In one aspect, the carrier(s) are particulate such that the compositions are, for example, in tablet or powdered form. The carrier(s) may be a liquid, the compositions being, for example, an oral syrup, an injectable liquid or an aerosol, which may be used in, for example, administration by inhalation.

When the pharmaceutical composition is intended for oral administration, it is preferably in solid or liquid form, with semi-solid, semi-liquid, suspension and gel forms included in the forms, which are considered here as solid or liquid.

As a solid composition for oral administration, the pharmaceutical composition may be formulated into a powder, granule, compressed tablet, pill, capsule, chewing gum, wafer, or the like. Such a solid composition usually contains one or more inert diluents or food carriers. In addition, one or more of the following may be present: binders such as carboxymethylcellulose, ethylcellulose, microcrystalline cellulose, tragacanth, or gelatin; excipients such as starch, lactose or dextrins; disintegrants such as alginic acid, sodium alginate, primogel, corn starch and the like; lubricants such as magnesium stearate or Sterotex; glidants such as colloidal silicon dioxide; sweeteners such as sucrose or saccharin; flavors such as peppermint, methyl salicylate, or orange flavor; and dye.

When the pharmaceutical composition is in the form of a capsule, for example a gelatin capsule, it may contain, in addition to materials of the above type, a liquid carrier such as polyethylene glycol or an oil.

The pharmaceutical composition may be in the form of a liquid, such as an elixir, syrup, solution, emulsion or suspension. The liquid may be for oral administration or for delivery by injection, as two examples. When intended for oral administration, a preferred composition contains, in addition to the compounds of the invention, one or more sweeteners, preservatives, dyes/colors and flavor enhancers. Compositions intended for administration by injection may include one or more of a surfactant, a preservative, a wetting agent, a dispersing agent, a suspending agent, a buffer, a stabilizer, and an isotonic agent.

Liquid pharmaceutical compositions of the invention, which may be solutions, suspensions or other forms, may include one or more of the following adjuvants: sterile injectable diluents such as water, saline, preferably saline, Ringer's solution, isotonic sodium chloride, fixed oils such as synthetic mono- or diglycerides which may serve as a solvent or suspending medium, polyethylene glycols, glycerol, propylene glycol or other solvents; antibacterial agents such as benzyl alcohol or methylparaben; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as ethylenediaminetetraacetic acid; buffers such as acetates, citrates or phosphates; and agents for adjusting tonicity such as sodium chloride or dextrose. The parenteral preparation may be included in ampoules, disposable syringes or reusable glass or plastic ampoules. Physiological saline is the preferred adjuvant. The injectable pharmaceutical composition is preferably sterile.

A liquid pharmaceutical composition according to the invention, intended for parenteral or oral administration, should contain such an amount of the compound according to the invention in order to obtain a suitable dosage.

The pharmaceutical composition of the invention may be for topical administration, where the carrier may suitably comprise a solution, emulsion, ointment or gel base. The base, for example, may include one or more of the following: petroleum jelly, lanolin, polyethylene glycols, beeswax, mineral oil, diluents such as water and alcohol, and emulsifiers and stabilizers. Thickening agents may be present in the pharmaceutical composition for topical administration. If it is intended for transdermal administration, the composition may include a transdermal patch or iontophoresis device.

The pharmaceutical composition of the invention may be for rectal administration, in the form of, for example, a suppository, which will melt in the rectum and release the drug. The composition for rectal administration may contain an oil base as a suitable non-irritating excipient. Such bases include, without limitation, lanolin, cocoa butter, and polyethylene glycol.

The pharmaceutical composition of the invention may include various materials that modify the physical form of the solid or liquid dosage form. For example, the composition may include materials that form a shell around the active ingredients. The materials that form the shell are generally inert and may be selected from, for example, sugar, shellac, and other enteric coating agents. Alternatively, the active ingredients may be enclosed in a gelatin capsule.

A pharmaceutical composition of the invention in solid or liquid form may include an agent that binds to a compound of the invention and thus assists in the delivery of the compound. Suitable agents that can act in this way include a monoclonal or polyclonal antibody, protein, or liposome.

The pharmaceutical composition of the invention may be in dosage units which may be administered as an aerosol. The term aerosol is used to refer to various systems from those of a colloidal nature to systems consisting of sealed packages. Delivery can be by liquefied or compressed gas, or by a suitable pump system that dispenses the active ingredients. Aerosols of the compounds of the invention may be in single phase, biphasic or three phase systems delivering the active ingredient(s). Aerosol delivery includes the necessary container, activators, valves, hoists, and the like, which together may form a kit. The skilled artisan can determine preferred aerosols without further experimentation.

Pharmaceutical compositions according to the invention can be obtained in accordance with the methodology known in the field of pharmacy. For example, a pharmaceutical composition intended for administration by injection may be prepared by combining a compound of the invention with sterile distilled water to form a solution. A surfactant may be added to facilitate the formation of a homogeneous solution or suspension. Surfactants are compounds that interact non-covalently with a compound of the invention to facilitate dissolution or homogeneous suspension of the compound in an aqueous delivery system.

The compounds of the invention, or pharmaceutically acceptable salts thereof, are administered in a therapeutically effective amount which will vary depending on various factors, including the activity of the particular compound used; metabolic stability and duration of action of the compound; age, body weight, general health, sex and diet of the patient; method and time of administration; excretion rate; drug combinations; the severity of the specific disorder or condition; and therapy tolerated by the patient.

In some embodiments, a typical dosage of a substantially impermeable or substantially systemically non-bioavailable compound may be from about 0.2 mg per day to about 2 g per day, or between about 1 mg and about 1 g per day, or from about 5 mg up to about 500 mg, or from about 10 mg to about 250 mg per day, which is administered to the patient.

The frequency of administration of the compounds and compositions described herein may vary from once a day (QD) to twice a day (BID) or three times a day (TID), etc., and the exact frequency of administration varies depending on eg patient condition, dosage, etc.

The compounds of the invention, or pharmaceutically acceptable derivatives thereof, may also be administered simultaneously with, before or after the administration of one or more other therapeutic or biologically active agents, dietary supplements, or any combination thereof. Such combination therapy includes administering a single pharmaceutical formulation that contains a compound of the invention and one or more additional active agents, as well as administering a compound of the invention and each active agent in its own separate pharmaceutical formulation. For example, a compound of the invention and another active agent may be administered to a patient together in a single oral composition such as a tablet or capsule, or each agent may be administered in separate oral formulations. When separate formulations are used, the compounds of the invention and one or more additional active agents may be administered at substantially the same time, ie, simultaneously, or at separate staggered times, ie, sequentially; combination therapy is understood to include all of these regimens.

For example, in some embodiments, the additional biologically active agent included in the pharmaceutical composition (or method) according to the invention is selected, for example, from vitamin D₂ (ergocalciferol), vitamin D₃ (cholecalciferol), active vitamin D (calcitriol), and active vitamin D analogs (eg doxercalciferol, paricalcitol).

In other embodiments, the additional biologically active agent included in the pharmaceutical composition (or method) of the invention is a phosphate binder such as sevelamer (e.g., Renvela® (sevelamer carbonate), Renagel® (sevelamer hydrochloride)), lanthanum carbonate ( e.g. Fosrenol®), calcium carbonate (e.g. Calcichew®, Titralac®), calcium acetate (e.g. PhosLo®, Phosex®), calcium acetate/magnesium carbonate (e.g. Renepho®, OsvaRen®), MCI-196, citrate iron (eg Zerenex™), iron magnesium hydroxycarbonate (eg FeRmagate™), aluminum hydroxide (eg Alucaps®, Basaljel®), APS1585, SBR-759, PA-21, etc.

In some aspects, the compounds may act synergistically with phosphate binders to provide greater efficacy than the sum of the efficacy of the transport inhibitor and phosphate binder administered alone. Without being bound by theory, it is believed that the synergism results from different mechanisms of action of the phosphate transport inhibitor and the phosphate binder. More specifically, a phosphate transport inhibitor blocks epithelial internal transport of phosphate ions, while a phosphate binder sequesters free phosphate ions in the intestinal lumen.

The effectiveness of a phosphate binder, as measured by its in vivo binding capacity (moles of phosphate ions bound per gram of binder), is essentially dictated by: i) the density of the binding sites (i.e., the amino groups in Renvela® (sevelamer), a polymeric amine material; or polyvalent cations, such as calcium or lanthanum in PhosLo® (calcium acetate) or Fosrenol (lanthanum carbonate)); and ii) the affinity of said binding sites for phosphate ions. It should be noted that only a subset of the binding sites are available for in vivo phosphate binding because other anions such as bile acids and fatty acids compete for the binding sites and therefore reduce efficiency. Bound phosphate ions are in equilibrium with free phosphate in the intestinal lumen and are themselves subjected to intense pumping from phosphate transport proteins lining the epithelium. Experiments have shown that the efficiency of phosphate uptake in the intestine is high, exceeding 95% of the phosphate present on the epithelium. It is believed that active phosphate transport contributes to a decrease in the intracavitary concentration of free phosphate and therefore a shift in the binding equilibrium of the phosphate binder to a reduced binding capacity. It is also believed that the reduction of intestinal phosphate transport using a phosphate transport inhibitor restores the higher in vivo binding capacity of phosphate sequesters. The synergistic effect is believed to be even more pronounced when the contribution of active phosphate transport is increased by, for example, treatment with vitamin D, an agent that promotes NaPi2b expression.

In some embodiments, the additional biologically active agent is a sodium dependent intestinal phosphate transporter inhibitor (NaPi2b inhibitor). Examples of NaPi2b inhibitors can be found, for example, in international applications PCT/US2011/043267; PCT/US2011/043261; PCT/US2011/043232; PCT/US2011/043266; and PCT/US2011/043263; and US Pat. No. 8,134,015, each of which is incorporated by reference in its entirety.

In some embodiments, the additional biologically active agent is niacin or nicotinamide.

It should be understood that in the present specification, combinations of substituents and/or variables of the depicted formulas are only permitted if such combinations result in stable or acceptably stable compounds.

The skilled person will also appreciate that in the process described herein, the functional groups of the intermediates may need to be protected with suitable protecting groups. Such functional groups include hydroxy, amino, mercapto, and carboxylic acid. Suitable protecting groups for hydroxyl groups include trialkylsilyl or diarylalkylsilyl (eg, t-butyldimethylsilyl, t-butyldiphenylsilyl or trimethylsilyl), tetrahydropyranyl, benzyl, and the like. Suitable protecting groups for amino, amidine, and guanidino include t-butoxycarbonyl, benzyloxycarbonyl, and the like. Suitable protecting groups for mercapto include -C(O)-R'' (where R'' is alkyl, aryl, or arylalkyl), p-methoxybenzyl, trityl, and the like. Suitable protecting groups for a carboxylic acid include alkyl, aryl or arylalkyl esters. Protecting groups may be added or removed according to standard techniques known to those skilled in the art and as described herein. The use of protecting groups is described in detail in Green, T.W. and P.G.M. Wutz, Protective Groups in Organic Synthesis (1999), 3rd Ed., Wiley. As one skilled in the art will understand, the protecting group may also be a polymeric resin such as Wang resin, Rink resin, or 2-chlorotrityl chloride resin.

The skilled artisan will also appreciate that while such protected derivatives of the compounds of the invention may not have pharmacological activity, they may be administered to a mammal and thereafter metabolized in the body to form compounds of the invention that are pharmacologically active. Such derivatives may therefore be described as "prodrugs". All prodrugs of the compounds of the invention are included within the scope of the invention.

In addition, all compounds of the invention which exist in free base or acid form may be converted to their pharmaceutically acceptable salts by treatment with a suitable inorganic or organic base or acid by methods known to those skilled in the art. Salts of the compounds of the invention may be converted to their free base or acid form by standard techniques.

Definitions and Terminology

"Amino" refers to the -NH ₂ radical.

"Aminocarbonyl" refers to the radical -C(=O)NH ₂ .

"Carboxy" refers to the -CO ₂ H radical. "Carboxylate" refers to a salt or ester thereof.

"Cyano" refers to the -CN radical.

"Hydroxy" or "hydroxyl" refers to the -OH radical.

"Imino" refers to the radical =NH.

"Nitro" refers to a radical -NO₂.

"Oxo" or "carbonyl" refers to the radical =O.

"Thioxo" refers to the radical =S.

"Guanidinyl" (or "guanidine") refers to the radical -NHC(=NH)NH ₂ .

"Amidinyl" (or "amidine") refers to the radical -C(=NH)NH ₂ .

"Phosphate" refers to the radical -OP(=O)(OH) ₂ .

"Phosphonate" refers to the radical -P(=O)(OH) ₂ .

"Phosphinate" refers to the radical -PH(=O)OH, with each R ^a independently representing an alkyl group as defined herein.

"Sulfate" refers to the radical -OS(=O) ₂ OH.

"Sulfonate" or "hydroxysulfonyl" refers to the radical -S(=O) ₂ OH.

"Sulfinate" refers to the radical -S(=O)OH.

"Sulfonyl" refers to the group including the -SO ₂ - group. For example, "alkylsulfonyl" or "alkylsulfone" refers to the group -SO ₂ -R ^a in which R ^and denotes an alkyl group as defined here.

"Alkyl" refers to a straight or branched chain hydrocarbon radical consisting solely of carbon and hydrogen atoms that is saturated or unsaturated (i.e., contains one or more double and/or triple bonds) having from one to twelve carbon atoms ( C _1-12 alkyl), preferably from one to eight carbon atoms (C ₁ -C ₈ alkyl) or from one to six carbon atoms (C ₁ -C ₆ alkyl), and which is attached to the rest of the molecule by a single bond, for example, methyl, ethyl, n-propyl, 1-methylethyl (iso-propyl), n-butyl, n-pentyl, 1,1-dimethylethyl (tert-butyl), 3-methylhexyl, 2-methylhexyl, vinyl, prop-1- enyl, but-1-enyl, pent-1-enyl, pent-1,4-dienyl, ethynyl, propynyl, butynyl, pentynyl, hexynyl, and the like. Unless the specification specifically states otherwise, the alkyl group may be substituted.

"Alkylene" or "alkylene chain" refers to a straight or branched divalent hydrocarbon chain linking the remainder of the molecule to a radical group consisting solely of carbon and hydrogen that is saturated or unsaturated (i.e., contains one or more double and/or triple bonds), and having from one to twelve carbon atoms, for example, methylene, ethylene, propylene, n-butylene, ethenylene, propenylene, n-butenylene, propynylene, n-butynylene, and the like. The alkylene chain is attached to the rest of the molecule through a single or double bond and to the radical group through a single or double bond. The points of attachment of the alkylene chain to the rest of the molecule and to the radical group can be through one carbon or any two carbons in the chain. Unless the specification specifically states otherwise, the alkylene chain may be substituted.

"Alkoxy" refers to a radical of the formula -OR_a, where R_a denotes an alkyl radical, as defined above, containing from one to twelve carbon atoms. Unless specifically stated otherwise in the specification, the alkoxy group may be substituted.

"Alkylamino" refers to a radical of the formula -NHR_a or -NR_aR_a, where each R_a, independently, denotes an alkyl radical, as defined above, containing from one to twelve carbon atoms. Unless the specification specifically states otherwise, the alkylamino group may be substituted.

"Thioalkyl" refers to a radical of the formula -SR_a, where R_a denotes an alkyl radical, as defined above, containing from one to twelve carbon atoms. Unless specifically stated otherwise in the specification, the thioalkyl group may be substituted.

"Aryl" refers to a hydrocarbon ring system comprising hydrogen, 6 to 18 carbon atoms, and at least one aromatic ring. For the purposes of this invention, the aryl radical may be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may include fused or bridged ring systems. Aryl radicals include, but are not limited to, aryl radicals derived from aceanthrilene, acenaphthylene, acephenanthrilene, anthracene, azulene, benzene, chrysene, fluoranthene, fluorene, as -indacene, s -indacene, indan, indene, naphthalene, phenalene, phenanthrene, pleiaden, pyrene and triphenylene. Unless specifically stated otherwise in the specification, the term "aryl" or the prefix "ar-" (such as in "aralkyl") includes aryl radicals which may be substituted.

"Aralkyl" refers to a radical of the formula -R_b-R_c, where R_b denotes an alkylene chain as defined above and R_c represents one or more aryl radicals as defined above, for example, benzyl, diphenylmethyl, and the like. Unless the specification specifically states otherwise, the aralkyl group may be substituted.

"Cycloalkyl" or "carbocyclic ring" refers to a stable non-aromatic monocyclic or polycyclic hydrocarbon radical consisting solely of carbon and hydrogen atoms, which may include fused or bridged ring systems, having three to fifteen carbon atoms, preferably having three to ten carbon atoms, and which is saturated or unsaturated and attached to the rest of the molecule by a single bond. Monocyclic radicals include, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl. Polycyclic radicals include, for example, adamantyl, norbornyl, decalinyl, 7,7-dimethyl-bicyclo[2.2.1]heptanyl, and the like. Unless the specification specifically states otherwise, the cycloalkyl group may be substituted.

"Cycloalkylalkyl" refers to a radical of the formula -R_bR_d, where R_dis an alkylene chain as defined above, and R_g denotes a cycloalkyl radical as defined above. Unless the specification specifically states otherwise, the cycloalkylalkyl group may be substituted.

"Fused" refers to any ring structure described herein that is fused to an existing ring structure in the compounds of the invention. When the fused ring is a heterocyclyl ring or heteroaryl ring, any carbon atom on the existing ring structure that becomes part of the fused heterocyclyl ring or heteroaryl ring may be replaced by a nitrogen atom.

"Halogen" refers to bromine, chlorine, fluorine or iodine.

"Haloalkyl" refers to an alkyl radical as defined above which is substituted by one or more halogens as defined above, e.g. trifluoromethyl, difluoromethyl, trichloromethyl, 2,2,2-trifluoroethyl, 1,2-difluoroethyl, 3-bromo-2 -fluoropropyl, 1,2-dibromoethyl, and the like. Unless specifically stated otherwise in the specification, the haloalkyl group may be substituted. "Heterocyclyl" or "heterocyclic ring" refers to a stable 3-18 membered non-aromatic ring radical which is composed of two to twelve carbon atoms and one to six heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur. Unless the specification specifically states otherwise, the heterocyclyl radical may be a monocyclic, bicyclic, tricyclic, or tetracyclic ring system, which may include fused or bridged ring systems; and the nitrogen, carbon or sulfur atoms in the heterocyclyl radical may optionally be oxidized; the nitrogen atom may be quaternized if necessary; and the heterocyclyl radical may be partially or completely saturated. Examples of such heterocyclyl radicals include, but are not limited to, dioxolanyl, thienyl[1,3]dithianyl, decahydroisoquinolyl, imidazolinyl, imidazolidinyl, isothiazolidinyl, isoxazolidinyl, morpholinyl, octahydroindolyl, octahydroisoindolyl, 2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolidinyl, , piperidinyl, piperazinyl, 4-piperidonyl, pyrrolidinyl, pyrazolidinyl, quinuclidinyl, thiazolidinyl, tetrahydrofuryl, trithianyl, tetrahydropyranyl, thiomorpholinyl, thiamorpholinyl, 1-oxo-thiomorpholinyl, and 1,1-dioxo-thiomorpholinyl. Unless the specification specifically states otherwise, the heterocyclyl group may be substituted.

"N-heterocyclyl" refers to a heterocyclyl radical, as defined above, containing at least one nitrogen atom, and where the attachment of the heterocyclyl radical to the rest of the molecule is through the nitrogen atom in the heterocyclyl radical. Unless the specification specifically states otherwise, the N-heterocyclyl group may be substituted.

"Heterocyclylalkyl" refers to a radical of the formula -R _b R _e , where R _b denotes an alkylene chain as defined above and R _e denotes a heterocyclyl radical as defined above, and if heterocyclyl is a nitrogen-containing heterocyclyl, the heterocyclyl may be attached to the alkyl radical at nitrogen atom. Unless specifically stated otherwise in the specification, the heterocyclylalkyl group may be substituted.

"Heteroaryl" refers to a 5-14 membered ring system comprising hydrogen atoms, one to thirteen carbon atoms, one to six heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur, and at least one aromatic ring. For the purposes of this invention, the heteroaryl radical may be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may include fused or bridged ring systems; and the nitrogen, carbon or sulfur atoms in the heteroaryl radical may optionally be oxidized; the nitrogen atom may be quaternized if necessary. Examples include, but are not limited to, azepinyl, acridinyl, benzimidazolyl, benzothiazolyl, benzdolyl, benzodioxolyl, benzofuranyl, benzoxazolyl, benzothiazolyl, benzothiadiazolyl, benzo[ b ][1,4]dioxepinyl, 1,4-benzodioxanyl, benzonaphthofuranyl, benzoxazolyl, benzodioxolyl , benzodioxynyl, benzopyranyl, benzopyranonyl, benzofuranyl, benzofuranonyl, benzothienyl (benzothiophenyl), benzotriazolyl, benzo[4,6]imidazo[1,2-a]pyridinyl, carbazolyl, cinnolinyl, dibenzofuranyl, dibenzothiophenyl, furanyl, furanonyl, isothiazolyl, imidazolyl, indazolyl, indolyl, indazolyl, isoindolyl, indolinyl, isoindolinyl, isoquinolyl, indolizinyl, isoxazolyl, naphthyridinyl, oxadiazolyl, 2-oxoazepinyl, oxazolyl, oxiranyl, 1-oxidopyridinyl, 1-oxidopyrimidinyl, 1-oxidopyrazinyl, 1-oxidopyridazinyl, 1-phenyl- 1H-pyrrolyl, phenazinyl, phenothiazinyl, phenoxazinyl, phthalazinyl, pteridinyl, purinyl, pyrrolyl, pyrazolyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, quinazolinyl, quinoxalinyl, quinolinyl, quinuclide inyl, isoquinolinyl, tetrahydroquinolinyl, thiazolyl, thiadiazolyl, triazolyl, tetrazolyl, triazinyl, and thiophenyl (i.e., thienyl). Unless specifically stated otherwise in the specification, the heteroaryl group may be substituted.

"N-heteroaryl" refers to a heteroaryl radical, as defined above, containing at least one nitrogen atom, and where the attachment of the heteroaryl radical to the rest of the molecule is through the nitrogen atom in the heteroaryl radical. Unless the specification specifically states otherwise, the N-heteroaryl group may be substituted.

"Heteroarylalkyl" refers to a radical of the formula -R_bR_f, where R_b is an alkylene chain as defined above, and R_f denotes a heteroaryl radical as defined above. Unless specifically stated otherwise in the specification, the heteroarylalkyl group may be substituted.

The term "substituted" as used herein means any of the above groups (i.e., alkyl, alkylene, alkoxy, alkylamino, thioalkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, haloalkyl, heterocyclyl, N-heterocyclyl, heterocyclylalkyl, heteroaryl, N-heteroaryl and/or heteroarylalkyl) in which at least one hydrogen atom is replaced by a bond to an atom other than hydrogen, such as, but not limited to: a halogen atom such as F, Cl, Br, and I; an oxygen atom in groups such as hydroxyl groups, carboxyl groups, phosphate groups, sulfate groups, alkoxy groups and ester groups; a sulfur atom in groups such as thiol groups, thioalkyl groups, sulfinate groups, sulfonic groups, sulfonyl groups and sulfoxide groups; a phosphorus atom in groups such as phosphinate groups and phosphonate groups; a nitrogen atom in groups such as guanidines, amines, amides, alkylamines, dialkylamines, aromatic amines, alkylarylamines, diarylamines, N-oxides, imides and enamines; a silicon atom in groups such as trialkylsilyl groups, dialkylarylsilyl groups, alkyldiarylsilyl groups, and triarylsilyl groups; and other heteroatoms in various other groups. "Substituted" also means any of the above groups in which one or more hydrogen atoms are replaced by a higher order bond (eg double or triple bond) to a heteroatom such as oxygen in oxo, carbonyl, carboxyl group and ester groups; and nitrogen in groups such as imines, oximes, hydrazines and nitriles. For example, "substituted" includes any of the above groups in which one or more hydrogen atoms are replaced by -NR_gR_h, -NR_gC(=O)R_h, -NR_gC(=O)NR_gR_h, -NR_gC(=O)OR_h, -NR_gSO₂R_h, -OC(=O)NR_gR_h, -OR_g, -SR_g, -SOR_g, -SO₂R_g, -OSO₂R_g, -SO₂OR_g, =NSO₂R_g and -SO₂NR_gR_h. "Substituted" also means any of the above groups in which one or more hydrogen atoms are replaced by -C(=O)R_g, -C(=O)OR_g, -C(=O)NR_gR_h, -CH₂SO₂R_g, -CH₂SO₂NR_gR_h, -(CH₂CH₂O)₁-₁₀R_g, -(CH₂CH₂O)_2-10R_g, -(OCH₂CH₂)_1-10R_g and -(OCH₂CH₂)_2-10R_g. In these groups R_g and R_h are the same or different and are independently hydrogen, alkyl, alkoxy, alkylamino, thioalkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, haloalkyl, heterocyclyl, N-heterocyclyl, heterocyclylalkyl, heteroaryl, N-heteroaryl and/or heteroarylalkyl. "Substituted" also means any of the above groups in which one or more hydrogen atoms are replaced by a bond to amino, cyano, hydroxyl, imino, nitro, oxo, thioxo, halogen, alkyl, alkoxy, alkylamino, thioalkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, haloalkyl, heterocyclyl, N-heterocyclyl, heterocyclylalkyl, heteroaryl, N-heteroaryl and/or heteroarylalkyl. The above non-hydrogen groups are generally referred to herein as "substituents" or "non-hydrogen substituents". In addition, each of the above substituents may also be substituted with one or more of the above substituents.

The singular forms are used here in relation to one or more than one (ie, at least one) grammatical object. By way of example, "element" means one element or more than one element.

Approximately denotes an amount, level, value, number, frequency, percentage, size, mass, or length that varies by 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 % in relation to the specified amount, level, value, number, frequency, percentage, size, mass, length, or other unit described here.

The term "activates" refers to the application of physical, chemical, or biochemical conditions, substances, or processes to a receptor (eg, pore receptor) for structural change in a manner that allows the passage of ions, molecules, or other substances.

The term "active state" refers to the state or condition of the receptor outside of its resting state.

"Outflow" refers to the movement or flow of ions, molecules, or other substances from the intracellular space to the extracellular space.

"Enteral" administration refers to administration through the gastrointestinal tract, including oral, sublingual, sublabial, buccal and rectal administration, and including administration through a gastric or duodenal feeding tube.

The term "inactive state" refers to the state of the receptor in its original endogenous state, that is, its resting state.

The term "modulation" includes "increase" or "increase", as well as "decrease" or "attenuation", usually in a statistically significant or physiologically significant amount compared to the control. An "increased" or "boosted" amount is usually a "statistically significant" amount and may include an increase that is about 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1, 7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.3, 4.4, 4.6, 4.8, 5, 6, 7, 8, 9, 10, 15, 20, 30, 40, 50 or more times (e.g. 100, 200, 500, 1000 times) (including all whole numbers and decimals and between and above 1, e.g. 5.5 , 5.6, 5.7, 5.8, etc.) compared to the amount produced by the control (eg, no or less compound, other compound, or treatment) or to the amount at an earlier time point (eg , prior to compound treatment). A "reduced" or "reduced" amount is usually a "statistically significant" amount and may include 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11 %, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100% reduction (including all whole numbers and decimals and ranges in between) with respect to the amount or activity produced (o) control (eg, no or less compound, other compound, or treatment), or to an amount at an earlier time point (eg, prior to compound treatment).

"Prodrug" means a compound which can be converted under physiological conditions or by solvolysis to the biologically active compound of the invention. Thus, the term "prodrug" refers to a metabolic precursor of a compound of the invention that is pharmaceutically acceptable. The prodrug may be inactive when administered to a patient, but is converted in vivo to the active compound of the invention. Prodrugs are usually rapidly converted in vivo, leading to the parent compound of the invention, for example, by blood hydrolysis. The prodrug compound often provides advantages in terms of solubility, tissue compatibility, or delayed release in the mammalian body (see, Bundgard, H., Design of Prodrugs (1985), pp. 7-9, 21-24 (Elsevier, Amsterdam)). For a discussion of prodrugs, see Higuchi, T., et ah, A.C.S. Symposium Series, Vol. 14, and in Bioreversible Carriers in Drug Design, Ed. Edward B. Roche, American Pharmaceutical Association and Pergamon Press, 1987.

The term "prodrug" also includes any covalently linked carriers that release the active compound of the invention in vivo when such a prodrug is administered to a mammal. Prodrugs of a compound of the invention can be prepared by modifying the functional groups present on a compound of the invention in such a way that the modifications are cleaved, either by conventional manipulation or in vivo, to the parent compound of the invention. Prodrugs include compounds of the invention in which a hydroxy, amino, or mercapto group is attached to any group that, when a prodrug of the compound of the invention is administered to a mammal, is cleaved to form a free hydroxyl group, a free amino group, or a free mercapto group, respectively. Examples of prodrugs include, but are not limited to, acetate, formate, and benzoate alcohol derivatives or amide derivatives of amino functional groups in the compounds of the invention, and the like.

The invention disclosed herein also covers in vivo metabolites of the disclosed compounds. Such products may be formed due to, for example, oxidation, reduction, hydrolysis, amidation, esterification, and the like. of the administered compound, primarily due to enzymatic processes. Accordingly, the invention includes compounds produced by a process comprising administering a compound of the invention to a mammal for a time sufficient to result in a metabolite. Such products are typically identified by administering an isotopically labeled compound of the invention at a detectable dose to an animal such as a rat, mouse, guinea pig, monkey, or human, allowing sufficient time to metabolize, and isolating its metabolites from urine, blood, or other biological samples.

"Mammal" includes human and domestic animals such as laboratory animals and domestic animals (e.g., cats, dogs, pigs, cattle, sheep, goats, horses, rabbits) and non-domestic animals such as wild animals, etc. .

"If necessary" means that the event or circumstance described below may or may not occur, and that the description includes cases where the specified event or circumstance occurs and cases in which it does not. For example, "optionally substituted aryl" means that the aryl radical may or may not be substituted and that the description includes both substituted aryl radicals and aryl radicals without any substitution.

A "pharmaceutically acceptable carrier, diluent, or excipient" includes, without limitation, any adjuvant, carrier, excipient, glidant, sweetener, diluent, preservative, dye/colorant, flavor enhancer, surfactant, wetting agent, dispersing agent, suspending agent, stabilizer, an isotonic agent, diluent, or emulsifier that has been approved by the USPC as being acceptable for use in humans or pets.

A "pharmaceutically acceptable salt" includes acid and base addition salts.

A "pharmaceutically acceptable acid addition salt" refers to salts that retain the biological efficacy and free base properties that are not biologically or otherwise undesirable and that form with inorganic acids such as, but not limited to, hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and the like, and organic acids such as, but not limited to, acetic acid, 2,2-dichloroacetic acid, adipic acid, alginic acid, ascorbic acid, aspartic acid, benzenesulfonic acid, benzoic acid, 4-acetamidobenzoic acid, camphoric acid, camphor-10-sulfonic acid, capric acid, caproic acid, caprylic acid, carbonic acid, cinnamic acid, citric acid, cyclamic acid, dodecylsulfuric acid, ethane-1,2-disulfonic acid , ethanesulfonic acid, 2-hydroxyethanesulfonic acid, formic acid, fumaro ic acid, galactaric acid, gentisic acid, glucoheptonic acid, gluconic acid, glucuronic acid, glutamic acid, glutaric acid, 2-oxo-glutaric acid, glycerophosphoric acid, glycolic acid, hippuric acid, isobutyric acid, lactic acid, lactobionic acid, lauric acid acid, maleic acid, malic acid, malonic acid, mandelic acid, methanesulfonic acid, mucic acid, naphthalene-1,5-disulfonic acid, naphthalene-2-sulfonic acid, 1-hydroxy-2-naphthoic acid, nicotinic acid, oleic acid , orotic acid, oxalic acid, palmitic acid, pamoic acid, propionic acid, pyroglutamic acid, pyruvic acid, salicylic acid, 4-aminosalicylic acid, sebacic acid, stearic acid, succinic acid, tartaric acid, thiocyanic acid, p-toluenesulfonic acid, trifluoroacetic acid, undecylenic acid, and the like.

"A pharmaceutically acceptable base addition salt" refers to salts that retain the biological effectiveness and free acid properties that are not biologically or otherwise undesirable. These salts are obtained by adding an inorganic base or an organic base to a free acid. Salts derived from inorganic bases include, but are not limited to, sodium, potassium, lithium, ammonium, calcium, magnesium, iron, zinc, copper, manganese, aluminum salts, and the like. Preferred inorganic salts are the ammonium, sodium, potassium, calcium and magnesium salts. Salts derived from organic bases include, but are not limited to, salts of primary, secondary, and tertiary amines, substituted amines, including natural substituted amines, cyclic amines, and cation exchange resins such as ammonia, isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, diethanolamine, ethanolamine, deanol, 2-dimethylaminoethanol, 2-diethylaminoethanol, dicyclohexylamine, lysine, arginine, histidine, caffeine, procaine, hydrabamine, choline, betaine, benetamine, benzathine, ethylenediamine, glucosamine, methylglucamine, theobromine, triethanolamine, tromethamine, purine, piperazine, piperidine, N-ethylpiperidine, polyamine resins, and the like. Particularly preferred organic bases are isopropylamine, diethylamine, ethanolamine, trimethylamine, dicyclohexylamine, choline and caffeine.

Often, crystallization results in a solvate of the compound of the invention. In the context of the invention, the term "solvate" refers to an aggregate that includes one or more molecules of a compound of the invention with one or more solvent molecules. The solvent may be water, in which case the solvate may be a hydrate. Alternatively, the solvent may be an organic solvent. Thus, the compounds of the present invention may exist in hydrated, including monohydrate, dihydrate, hemihydrate, sesquihydrate, trihydrate, tetrahydrate, and the like, as well as corresponding solvated forms. The compound of the invention may be true solvates, while in other cases, the compound of the invention may simply retain adventitious water or be a mixture of water plus some adventitious solvent.

"Pharmaceutical composition" refers to the composition of a compound of the invention and a medium conventional in the art for delivering a biologically active compound to a mammal, eg, a human. Such a medium includes all pharmaceutically acceptable carriers, diluents or excipients.

The compounds of the invention, or pharmaceutically acceptable salts thereof, may contain one or more centers of asymmetry and may thus form enantiomers, diastereomers, and other stereoisomeric forms, which may be defined, in terms of absolute stereochemistry, as (R)- or (S )-, or as (D)- or (L)- for amino acids. The present invention includes all such possible isomers, as well as their racemic and optically pure forms. Optically active (+) and (-), (R)- and (S)- or (D)- and (L)-isomers can be obtained using chiral synthons or chiral reagents, or by separation using conventional techniques, for example, chromatography and fractional crystallization. Conventional techniques for the preparation/isolation of individual enantiomers include chiral synthesis from a suitable optically pure precursor or resolution of the racemate (or racemate of a salt or derivative) using, for example, chiral high performance liquid chromatography (HPLC). When the compounds described herein contain olefinic double bonds or other centers of geometric asymmetry, and unless otherwise indicated, this means that the compounds include geometric isomers E and Z. Similarly, all tautomeric forms are also included in the scope of the invention.

"Stable compound" and "stable structure" means a compound that is strong enough to undergo isolation in useful purity from a reaction mixture and formulation into an effective therapeutic agent.

By "statistically significant" is meant that the result could hardly have been obtained by chance. Statistical significance can be determined by any method known in the art. Commonly used measures of significance include the p-value, which is the frequency or probability that the observed event would occur if the null hypothesis were true. If the resulting p-value is less than the significance level, then the null hypothesis is rejected. In simple cases, the significance level is determined by a p-value of 0.05 or less.

"Essentially" or "essentially" includes almost all or all of, for example, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more of some given amount.

The term "secondary" refers to a condition or condition that may occur with another disease status, condition, or treatment, may follow another disease status, condition, or treatment, or may result from another disease status, condition, or treatment. The term also refers to situations where the disease status, condition, or treatment may play only a minor role in shaping the symptoms or response in the patient's final disease status, symptoms, or condition.

"Individuals" or "patients" (these terms are used interchangeably herein) who require treatment with a compound of the present disclosure include, for example, patients "for whom there is a need for phosphate reduction." Included are mammals with the diseases and/or conditions described herein, especially the diseases and/or conditions that can be treated with the compounds of the invention, with or without other active agents, to achieve a beneficial therapeutic and/or prophylactic result. Beneficial outcomes include a reduction in the severity of symptoms or a delay in the onset of symptoms, modulation of one or more of the features described herein (eg, decreased serum or blood phosphate ion levels in patients with or at risk of hyperphosphatemia, increased excretion of phosphate ions in the feces in patients with or with hyperphosphatemia). risk of hyperphosphatemia), increased life expectancy and/or faster or more complete cure of a disease or condition.

"Stereoisomer" refers to a compound composed of the same atoms joined by the same bonds, but having different spatial structures that are not interchangeable. The present invention contemplates various stereoisomers and mixtures thereof and includes "enantiomers" which refer to two stereoisomers whose molecules are non-superimposable mirror images of each other.

"Tautomer" refers to a proton shift from one atom of a molecule to another atom of the same molecule. The present invention includes tautomers of any of these compounds.

A "therapeutically effective amount" or "effective amount" includes an amount of a compound of the invention which, when administered to a mammal, preferably a human, is sufficient to inhibit or otherwise decrease phosphate ion transport from the gastrointestinal lumen, increase fecal excretion of phosphate ions, decrease serum levels of phosphate ions, treatment of hyperphosphatemia in a mammal, preferably a human, and/or treatment of one or more of the other conditions described herein. The amount of a compound of the invention that constitutes a "therapeutically effective amount" varies depending on the compound, the condition and its severity, the route of administration, and the age of the mammal being treated, but can be determined in a conventional manner by one of skill in the art based on one's own knowledge and this disclosure.

"Treatment" within the meaning of the invention encompasses the treatment of a disease or condition in a mammal, preferably a human, having that disease or condition, and includes:

(i) preventing the occurrence of a disease or condition in a mammal, in particular where such mammal is predisposed to the condition but has not yet been diagnosed as having it;

(ii) inhibiting the disease or condition, that is, arresting its progress;

(iii) elimination of the disease or condition, that is, regression of the disease or condition; or

(iv) the elimination of symptoms resulting from the disease or condition, ie, the reduction of pain, without affecting the underlying disease or condition. Within the scope of the invention, the terms "disease" and "condition" may be used interchangeably or may differ in that the specific disease or condition may not have a known causative agent (so that the etiology has not yet been worked out) and therefore is not yet recognized as a disease, but only as an undesirable condition or syndrome, with a more or less defined set of symptoms being identified by clinical specialists.

EXAMPLES

The following Examples, given by way of illustration and not limitation, illustrate various methods for preparing the compounds of the invention. It should be understood that the specialist can get these compounds by similar methods or a combination of other methods known to the expert. It should also be understood that, similar to what is described below, other compounds of the invention, not specifically illustrated below, can be prepared by one skilled in the art by using suitable starting materials and modifying the synthesis parameters if necessary. In general, starting components may be obtained from sources such as Sigma Aldrich, Lancaster Synthesis, Inc., Maybridge, Matrix Scientific, TCI, and Fluorochem USA, etc., or may be synthesized according to sources known to those skilled in the art (see , for example, Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 5th edition (Wiley, December 2000)), or obtained as described here.

The skilled person will also appreciate that in the process described herein, the functional groups of the intermediates may need to be protected with suitable protecting groups. Such functional groups include hydroxy, amino, mercapto, and carboxylic acid. Suitable protecting groups for hydroxy groups include trialkylsilyl or diarylalkylsilyl (eg, t-butyldimethylsilyl, t-butyldiphenylsilyl or trimethylsilyl), tetrahydropyranyl, benzyl, and the like. Suitable protecting groups for amino, amidino, and guanidino include t-butoxycarbonyl, benzyloxycarbonyl, and the like. Suitable protecting groups for mercapto groups include -C(O)-R'' (where R'' is alkyl, aryl, or arylalkyl), p-methoxybenzyl, trityl, and the like. Suitable protecting groups for a carboxylic acid include alkyl, aryl or arylalkyl esters. Protecting groups may be added or removed according to standard techniques known to those skilled in the art and as described herein. The use of protecting groups is described in detail in Green, T.W. and P.G.M. Wutz, Protective Groups in Organic Synthesis (1999), 3rd Ed., Wiley. As one skilled in the art will appreciate, the protecting group may also be a polymeric resin such as Wang resin, Rink resin, or 2-chlorotrityl chloride resin.

In addition, all compounds of the invention which exist in free base or acid form may be converted to their pharmaceutically acceptable salts by treatment with a suitable inorganic or organic base or acid by methods known to those skilled in the art. Salts of the compounds of the invention may be converted to their free base or acid form by standard techniques.

EXAMPLE 1

CELL-BASED ACTIVITY IN NHE3 INHIBITION AND INTESTINAL SODIUM AND PHOSPHATE ABSORPTION INHIBITION

The compounds in Table E1, or their pharmaceutically acceptable salts below, were tested in a cell-based assay for inhibition of NHE3 under fast conditions (rapid inhibition). These compounds were also tested for their ability to inhibit sodium and phosphate absorption in the intestinal lumen of rats.

Cell-based activity under fast conditions. Rat or human NHE3-mediated Na⁺-dependent H⁺ antiport was measured using the pH sensitive staining method originally described by Paradiso (PNAS USA. 81:7436-7440, 1984). Possum kidney (OK) cells were obtained from ATCC and propagated according to the instructions. Rat NHE3 gene (GenBank M85300) or human NHE3 gene (GenBank NM 004174.1) were introduced into TC cells by electroporation and the cells were seeded in 96-well plates and grown overnight. The medium was aspirated from the wells, the cells were washed twice with NaCl-HEPES buffer (100 mM NaCl, 50 mM HEPES, 10 mM glucose, 5 mM KCl, 2 mM CaCl₂, 1 mM MgCl₂, pH 7.4), then incubated for 30 minutes at room temperature with buffer NH_fourCl-HEPES (20 mM NH_fourC1, 80 mM NaCl, 50 mM HEPES, 5 mM KCl, 2 mM CaCl₂, 1 mM MgCl₂, pH 7.4) containing 5 µM bis(acetoxymethyl)-3,3'-(3',6'-bis(acetoxymethoxy)-5-((acetoxymethoxy)carbonyl)-3-oxo-3H-spiro[isobenzofuran-1 ,9'-xanthene]-2',7'-diyl)dipropanoate (BCECF-AM).

Cells were washed twice without ammonium and Na⁺ HEPES (100 mM choline, 50 mM HEPES, 10 mM glucose, 5 mM KCl, 2 mM CaCl₂, 1 mM MgCl₂, pH 7.4) and incubated in the same buffer for 10 minutes at room temperature to lower the intracellular pH. NHE3-mediated restoration of neutral intracellular pH was initiated by adding a Na-HEPES buffer containing 0.4 μM ethyl isopropyl amiloride (EIPA, a selective NHE-1 activity antagonist that does not inhibit NHE3) and 0-30 μM test compound, or a pharmaceutically acceptable salt, and monitoring pH-sensitive changes in BCECF fluorescence (λ_ex 505 nm λ_em 538 nm) normalized to pH-insensitive BCECF fluorescence (λ_ex 439 nm λ_em 538 nm). Baseline scores were plotted as averages of 2 or more measurements, and values pIC₅₀ evaluated using GraphPad Prism. The results are presented below in Table E3.

Inhibition of intestinal absorption of sodium and phosphate. Urinary sodium concentration and fecal form were measured to assess the ability of exemplary compounds to inhibit sodium absorption from the intestinal lumen. Eight week old Sprague-Dawley rats were purchased from Charles River Laboratories (Hollister, Calif.), housed 2 per cage, and acclimatized for at least 3 days before the start of the study. Animals were fed Harlan Teklad Global 2018 Rodent Food (Indianapolis, IN) and water ad libitum during the study and maintained on a standard 6:00-18:00 light-dark cycle. On the day of the study, between 4:00 pm and 5:00 pm, a group of rats (n=6) were orally fed the test compound or a pharmaceutically acceptable salt or vehicle (water) in a volume of 10 ml/kg.

After dosing, the animals were housed in individual metabolic cages where they were also fed the same chow in the form of food and given water ad libitum. Urine samples were collected 16 hours after administration and the fecal form was assessed by two independent observations. Fecal shapes were assessed according to the overall scale associated with the increase in faecal water to the wettest observed in the collection funnel with which the cells were equipped (1, normal ball; 2, ball sticking to the walls of the collection funnel due to moisture; 3, loss of normal shape ball; 4, complete loss of shape with signs of getting wet; 5, clear liquid fecal streams). Rat fecal shape score (FFS) was determined by averaging both observed scores for all rats within the group (n=6). The median for the carrier group was 1.

For urine samples, volumes were determined gravimetrically and centrifuged at 3,600 xg. Supernatants were diluted 100-fold in Milli-Q deionized water, then filtered through a 0.2 μm GHP Pall AcroPrep filter plate (Pall Life Sciences, Ann Arbor, MI) and then analyzed by ion chromatography. Ten microliters of each filtered extract was injected onto a Dionex ICS-3000 ionic system (Dionex, Sunnyvale, CA). Cations were separated isocratically using 25 mM methanesulfonic acid as eluent on an IonPac CS12A 2 mm ID cation exchange column. × 250 mm, 8 µm particle size (Dionex). Sodium was quantified using standards prepared from a standard cation mixture containing Li ⁺ , Na ⁺ , NH ₄ ⁺ , K ⁺ , Mg ²⁺ and Ca ²⁺ (Dionex). The mean weight of sodium excreted in urine was determined for each group over a period of 16 hours, while in the vehicle group, the weight of sodium excreted in urine was typically approximately 21 mg. The amount of Na in the urine (uNa) for rats in the test groups was expressed as a percentage of the mean for the vehicle, and the mean was compared with that of the vehicle group using one-way ANOVA together with Dunnett's retrospective test. The results are shown below in Table E3 .

Table E3

EXAMPLE 2

CELL-BASED TEST FOR NHE3 ACTIVITY IN RAPID AND CONSTANT CONDITIONS

The compounds shown in Table E4 below, or a pharmaceutically acceptable salt thereof, were tested in a cell-based assay for inhibition of NHE3 under fast conditions (rapid inhibition) and constant conditions (persistent inhibition). These compounds were also tested in a cell based assay for NaP2b activity.

Cell Based Activity NHE3 activities in 'Fast' conditions. This test was carried out as described in Example 1 (above).

Cell Based Activity NHE3 activities under 'Constant' conditions. The ability of the compounds to inhibit the Rat NHE3-mediated Na ⁺ -dependent H ⁺ antiport after application and washing was measured using the pH sensitive staining method described above. Possum kidney (OK) cells were obtained from ATCC and propagated according to the instructions. The rat NHE3 gene was introduced into OK cells by electroporation and the cells were plated in 96-well plates and grown overnight. The medium was aspirated from the wells, the cells were washed twice with NaCl-HEPES buffer (100 mM NaCl, 50 mM HEPES, 10 mM glucose, 5 mM KCl, 2 mM CaCl ₂ , 1 mM MgCl ₂ , pH 7.4), then covered with NaCl-HEPES buffer, containing 0-30 μM of test compounds.

After 60 min. incubation, the test drug containing the buffer was aspirated from the cells, the cells were washed twice with NaCl-HEPES buffer without drug, then incubated for 30 minutes at room temperature with buffer NH_fourCl-HEPES (20 mM NH_fourC1, 80 mM NaCl, 50 mM HEPES, 5 mM KCl, 2 mM CaCl₂, 1 mM MgCl₂, pH 7.4) containing 5 μM BCECF-AM. Cells were washed twice without ammonium and Na⁺ HEPES (100 mM choline, 50 mM HEPES, 10 mM glucose, 5 mM KCl, 2 mM CaCl₂, 1 mM MgCl₂, pH 7.4) and incubated in the same buffer for 10 minutes at room temperature to lower the intracellular pH. NHE3-mediated restoration of neutral intracellular pH was initiated (40 minutes after washing the compound) by adding Na-HEPES buffer containing 0.4 μM ethyl isopropyl amiloride (EIPA, a selective NHE-1 activity antagonist that does not inhibit NHE3) and pH monitoring. sensitive changes in BCECF fluorescence (λ_ex 505 nm λ_em 538 nm) normalized to pH-insensitive BCECF fluorescence (λ_ex 439 nm λ_em 538 nm). Baseline scores were plotted as averages of 2 or more measurements, and values pIC₅₀ evaluated using GraphPad Prism.

Cell-based NaP2b activity test. The degree of phosphate uptake (Pi) into the cells was measured using a modification of the method described in the literature (see, Mohrmann et al. Am. J. Phys. 250(3 pt l):G323-30, 1986). Briefly, HEK293 cells were transiently transfected with an expression clone encoding rat or human NaP2b. The next day, the transfected cells were treated with a pharmacological agent to minimize endogenous PiT-mediated phosphate transport activity, so that the only remaining sodium-dependent phosphate transport activity was provided by the introduction of the NaP2b gene. Cells were incubated with radioactive inorganic phosphate in the presence or absence of varying concentrations of the test compound. After a short time, the cells were washed, collected, and the amount of hot phosphate trapped in the cells was determined by liquid scintillation counting.

HEK293 cells were obtained from the American Type Culture collection and expanded according to the instructions. Rat and human NaP2b expression clones (SLC34A2) were obtained from Open Biosystems (catalog numbers MRN1768-9510282 and MHS 1010-99823026, respectively). There are two hypothetical splicing variants of human NaP2b, defined as isoform a and isoform b (NCBI reference sequences: NP 006415.2 and NP 001 171470.1, respectively). The sequence of the open reading frame MHS1010-99823026 corresponds to isoform b; transfection with this construct was found to provide only very low levels of non-endogenous Pi transport activity. The cDNA was therefore mutated to conform to isoform a; transfection with this sequence provided Pi transport significantly higher than background. Thus, only isoform a was used in human NaP2b inhibition studies.

Cells were seeded in 96-well plates at a density of 25,000 cells/well and cultured overnight. Lipofectamine 2000 (Invitrogen) was used to introduce the NaP2b cDNA and the cells were allowed to approach confluence during a second overnight incubation. The medium was aspirated from the cultures and the cells were washed once with choline capture buffer (14 mM Tris, 137 mM choline chloride, 5.4 mM KCl, 2.8 mM CaCl ₂ , 1.2 mM MgSO ₄ , 100 μM KH ₂ PO ₄ , 1 mg/ml BSA , pH 7.4). Cells were then coated with either choline capture buffer or sodium capture buffer (14 mM Tris, 137 mM choline chloride, 5.4 mM KCl, 2.8 mM CaCl ₂ , 1.2 mM MgSO ₄ , 100 μM KH ₂ PO ₄ , PiT inhibitor, 1 mg /ml Bovine serum albumin, pH 7.4) containing 6-9 uCi/ml ³³ P phosphoric acid (Perkin Elmer) and test compound. Each compound was tested at twelve concentrations ranging from 0.1 nM to 30 μM. Tests were run in duplicate and compounds of interest were tested multiple times. After incubation for 23 minutes at room temperature, the test mixtures were removed and the cells were washed twice with ice-cold stop solution (137 mM sodium chloride, 14 mM Tris, pH 7.4). Cells were dissolved by adding 20 µl of 0.1% Tween 80 followed by 100 µl of scintillation fluid and counted using a TopCount (Perkin Elmer). pIC ₅₀ values (negative log IC ₅₀ ) of test compounds were calculated using GraphPad Prism. Preliminary studies have shown that under these conditions, sodium-dependent Pi uptake was linear for at least 30 minutes and tolerated 0.6% (v/v) DMSO without deleterious effects. The results are presented below in Table E5 .

Table E5 NHE3 rats NHE3 person Compound pIC ₅₀
quick pIC ₅₀
constant pIC ₅₀
quick pIC ₅₀
constant pIC ₅₀
human NaP2b ^001a 7.6 nd 7.4 nd nd ^002b 8 8.4 8 8.2 <4.5 ^003b 8.6 nd 8 8.1 nd ^004b 7.3 5.6 7.3 5.6 Nd ^005b <5.0 nd <5.0 nd nd ^a Compound 001 was tested as the free base. ^b Compounds 002, 003, 004, and 005 were tested as the dihydrochloride salt.

Further experiments were performed to test the compounds under the constant and rapid conditions described above and to test their effects on sodium excretion in the urine of rats. The latter were performed by administering compounds orally to rats (single dose) and measuring urinary Na excretion (as % of vehicle). Results are shown as percentage of urinary sodium (UNa %); low values indicate relatively active compounds. The results are shown below in Table E6 .

Table E6 Compound pIC ₅₀
quick pIC ₅₀
constant Una (%) 001 ^a 7.4 nd 41 @ 1mg/kg ^002b 8 8.2 11 @ 1mg/kg ^003b 8 8.1 22 @ 1mg/kg ^004b 7.3 5.6 68 @ 1mg/kg ^005b <5.0 nd 90 @ 1mg/kg ^a Compound 001 was tested as the free base. ^b Compounds 002, 003, 004, and 005 were tested as the dihydrochloride salt.

These results identified compounds 002 and 003 as persistent inhibitors of the NHE3-mediated Na ⁺ -dependent H ⁺ antiport, and compound 004 as a non-persistent inhibitor of the NHE3-mediated Na ⁺ -dependent H ⁺ antiport. Compound 005 was considered inactive.

EXAMPLE 3

PHARMACODYNAMIC STUDIES WITH ³³ P ORAL PROVOCATION IN NORMAL FUNCTION RATS

Compounds identified as Comp. 003, 004 and 005 (from Table E4 in the form of their dihydrochloride salts) were tested for their ability to block intestinal phosphate uptake in rats. Rats were challenged orally with solutions composed of 5 ml/kg (-1.3 ml) of 8 mM Pi with ³³ P and +/- 10 mg/kg of test compound. Also included is the administration of solutions further formulated with either (i) 75 mM glucose + 4 mM Ca or (ii) 4 mM Ca.

The results are shown in Figures 1A-1C . Figure 1A shows that Conn. 004, a non-permanent inhibitor of NHE3 (ie, no significant effect on urinary Na and fecal form), was just as potent in reducing Pi uptake as a persistent inhibitor such as Comm. 003 (i.e., inducing a significant decrease in UNa and changes in fecal shape). Comm. 005 was inactive in this test. Figures 1B-C show that Comm. 003 significantly reduced Pi uptake in the presence of Glucose/Ca (1B) and Ca (1C) .

EXAMPLE 4

EFFECTS ON A RAT MODEL OF UREMIA-ASSOCIATED VASCULAR CALCINOSIS

Chronic kidney disease (CKD) has multiple pathogenic mechanisms, and advanced CKD is often characterized by impaired mineral metabolism (eg, hyperphosphatemia, hypercalcemia) and vascular calcification. Studies were carried out in such a way as to test the effectiveness of the dihydrochloride salt Comp. 002 (from Table E4, as the dihydrochloride salt) in a uremic rat CKD model showing vascular calcification. This model is characterized by kidney failure and regular administration of active vitamin D.₃ to promote hyperphosphatemia and vascular calcification (see Lopez et al., J. Am. Soc. Nephrol. 17:795-804, 2006). This study used Spraque-Dawley rats treated as follows: nephrectomy 5/6 by excision; regular administration of calcitriol (active vitamin D₃) 80 ng/kg ip 3/week; and feeding a purified 0.9% P diet (inorganic phosphorus).

Rats were stratified into two experimental groups for serum creatinine levels from 0.8 to 1.5 mg/dL and body weight, fed powdered chow with carrier or the same chow with Comp. 002 (0.065 mg/g feed) mixed into the feed and checked for weekly body weight change and selected serum parameters, daily clinical observations were made and final calcification was monitored. The design of the study is illustrated in Figure 2 .

Selected experimental groups were fed vehicle (n=l2) or Comp. 002 (n=l2) at registration (day 0). As shown in Figures 3A-F , baseline body weights and selected serum parameters such as serum phosphorus, serum calcium, serum creatinine, and blood urea nitrogen were comparable for both groups.

Selected final plasma parameters from day 27 are shown in Figures 4A-F . These data demonstrate a decrease in plasma creatinine, a decrease in plasma phosphorus, and a decrease in plasma FGF-23.

The final mass of the heart and kidneys is shown in Figure 5 . These data show that cardiac and renal hypertrophy was less in rats treated with Comp. 002. Given the reduced plasma creatinine, these results suggest that the renal residue in rats treated with Comp. 002, has more functionality with less weight.

Endpoint creatinine clearance (C _Cr ) and plasma levels of aldosterone are shown in Figures 6A-B . These results suggest that the treatment of Comp. 002 protects against loss of kidney function and the increase in aldosterone suggests some volume loss that is consistent with decreased Na uptake.

The final calcification of vessels and soft tissues is shown in Figures 7A-B . These data show that the treatment of Comm. 002 reduced calcium and phosphorus in the stomach, which is particularly susceptible to calcification, and also reduced vascular calcification as measured by aortic mineral content.

In general, it has been shown that Comm. 002 improves renal function, reduces both cardiac and renal hypertrophy, shows antihyperphosphatemic effects, and reduces associated vascular calcification. These effects and reduced morbidity were observed in the treatment group, with a trend towards improved mortality rates. Although the benefits of treatment with Comm. 002 may in part be due to its effect on fluid overload and hemodynamics, because vascular calcification in this model is highly sensitive to dietary phosphate, a reduction in ectopic calcification indicating a reduction in phosphate absorption.

EXAMPLE 5

EFFECTS ON ADENNINE-INDUCED UREMIC RAT MODEL

Effects 002 (from Table E4, in the form of the dihydrochloride salt) were tested in an adenine-induced uremic rat model. Rats were fed a diet containing 0.75% adenine and 1.2% phosphorus during the induction phase of nephritis. The main diet during the treatment phase was a normal food containing 0.3% adenine and 0.6% phosphorus for 2 weeks. The rats were fed identically for 5 days (groups 1 and 2 to group 3 with an interval of 4 days) and then fed ad libitum. The treatment groups were as follows: vehicle, n = 10; Comm. 002, drug in feed 2 mg/kg/day, n=10; and Comm. 002, feed drug 5 mg/kg/day, n=12. Serum markers and renal function were measured weekly. The design of the study is illustrated in Figure 8A .

As shown in Figures 8B-C , Conn. 002 reduced serum phosphorus and serum creatinine at early time points. Here, this adenine-induced model is considered an acute kidney injury characterized by progressive recovery of renal function. Therefore, the effects at early time points are significant.

Organ weight data from week three are shown in Figures 9A-B and tissue mineralization data from week three are shown in Figures 10A-B . These data show that the treatment of Comm. 002 in this model showed a trend towards less cardiac and renal remodeling, and a trend towards reduced cardiac and renal calcification at the highest dose.

EXAMPLE 6

EFFECT ON RENAL INSUFFICIENCY WITH HIGH SALT CONSUMPTION IN NEPHRECTOMY RATS

Effects 002 (from Table E4, in the form of the dihydrochloride salt) was tested in a salt-induced partial renal ablation model of CKD. The design of the study is illustrated in Figure 11A (12 rats per group). Figure 11B illustrates the effects of Comm. 002 for urinary phosphorus excretion. In this study, Comm. 002 improved blood pressure, fluid overload, albuminuria, and cardiac and renal hypertrophy, and significantly reduced urinary phosphorus excretion. These data suggest an additive contribution to the reduction of phosphorus Comm. 002 to improve renal and vascular functions.

EXAMPLE 7

Effects on Urinary Phosphate and Calcium Excretion in Rats

Activity 002 (from Table E4, in the form of the dihydrochloride salt) was tested for effects on urinary phosphorus and calcium levels in rats. Rats were administered according to the plan in Table E7.

Table E7 Groups 929uP Introduction #1 Intro #2 10 min later 1 Water Water 2 Renvela® (sevelamer), 48 mg/kg Water 3 Water Comm. 002, 0.1 mg/kg four Water Comm. 002, 0.3mg/kg five Water Comm. 002, 1.0 mg/kg 6 Water Comm. 002, 3.0 mg/kg

Rats were kept for 16 hours overnight (in the dark, a typical feeding period) in individual metabolic cages} and urine was collected the next morning for analysis of calcium and phosphate levels. The design of the study is shown in Figure 12 . The results are shown in Figures 13A-D . These results show that Comm. 002 reduced both urinary phosphorus mass and urinary calcium mass relative to the vehicle-only control group. Increase in dosages Comm. 002 also significantly reduced urinary phosphorus mass relative to Renvela® at 48 mg/kg.

EXAMPLE 8

EVALUATION OF ACTIVITY IN REDUCING DIETARY PHOSPHORUS AT A DOSE OF 15, 30 AND 60 MG TID IN A 7-DAY RE-DOSE STUDY IN HEALTHY VOLUNTEERS

A single-center, randomized, double-blind, placebo-controlled, Phase 1 study was designed to evaluate the safety, tolerance, and pharmacodynamic activity (PD) on sodium and phosphorus excretion of various regimens of Comp. 002, in the form of the dihydrochloride salt, (see Table E4) in healthy male and female patients.

Patients were screened for 3 weeks prior to enrollment and assigned sequentially to groups in order of completion of screening studies. Each group of 15 patients was registered at the Clinical Pharmacology Unit (CPU) on Day -5 before lunch. Patients were continuously in the CPU and received Na+-standard nutrition (-1500 mg/dose).

In each group, 12 patients were randomized to receive Comp. 002 and 3 patients - placebo.

Patients received doses of Comm. 002 with approximately 240 ml of non-carbonated water on Days 1 to 7 (immediately before meals, depending on twice a day [breakfast, lunch]. Patients were given standardized food within 10 minutes after administration.

Study Population Selection - Inclusion Criteria . Patients were eligible for inclusion in the study if they met all of the following criteria:

1. Healthy male or female aged 19 - 65 years, inclusive.

2. Body mass index (BMI) from 18 to 29.9 kg/m ² inclusive.

3. Absence of clinically significant abnormalities on history, physical examination, or clinical laboratory evaluations at screening.

4. Ability to understand and follow protocol.

5. Willingness and ability to sign informed consent.

6. Women were not pregnant, lactating, and either postmenopausal for at least 12 months, as confirmed by follicle-stimulating hormone (FSH) testing, or were surgically sterilized (eg, tubal ligation, hysterectomy, bilateral oophorectomy with documentation) for at least 90 days, or agreed to use from the time of signing the informed consent until 45 days after the end of the study, 1 of the following forms of contraception: intrauterine device with spermicide, female condom with spermicide, contraceptive sponge with spermicide, diaphragm with spermicide, cervical cap with spermicide, male sexual partner who agrees to use a male condom with spermicide, infertile sexual partner, abstinence, intravaginal system (eg, NuvAring®) with spermicide, or oral, implantable, percutaneous, or injectable contraceptives oral preparations with spermicide.

7. Men were either infertile, abstaining, or willing to use, from enrollment to 45 days from final study visit, 1 of the following approved methods of contraception: male condom with spermicide; infertile sexual partner; use by a female sexual partner of a spermicide intrauterine device, spermicide female condom, spermicide sponge, intravaginal system (eg, NuvAring), spermicide diaphragm, spermicide cervical cap, or oral, implantable, percutaneous, or injectable contraceptives).

Study Population Selection - Exclusion Criteria . Patients were excluded from the study if they met any of the following criteria:

1. Diagnosis or treatment of any clinically characteristic biochemical or structural abnormality of the gastrointestinal system.

2. Any surgery on the small intestine or large intestine, excluding appendectomy or cholecystectomy.

3. Clinically evident presence of significant cardiovascular, respiratory, renal, hepatic, gastrointestinal, hematological, metabolic, endocrine, neurological, psychiatric disease, or any condition that may prevent the patient from successfully completing the test.

4. Frequent loose stools (BSFS 6 or 7) > 2 days in previous 7 days.

5. Hepatic dysfunction (alanine aminotransaminase [ALT] or aspartate aminotransaminase [AST]) > 1.5 times upper limit of normal [ULN]) or kidney damage (serum creatinine > ULN).

6. Clinically significant laboratory results at screening, as determined by the investigator.

7. Any obvious presence or treatment of malignancy, excluding non-melanomatous skin cancers.

8. If, in the opinion of the Investigator, the patient was unable or unwilling to comply with protocol requirements or had a condition that rendered the results uninterpretable.

9. Diet that, in the opinion of the investigator, may have confounded the results of the study.

10. Use of diuretics; treatments known to affect stool consistency and/or gastrointestinal motility, including fiber supplements (unless required for research), antidiarrheal drugs, laxatives, antacids, opiates, sleeping pills, prokinetic drugs, enemas , antibiotics, probiotic medicines or supplements; or salts or electrolyte supplements containing Na ⁺ , potassium, chloride or bicarbonate compounds from registration at the CPU (Day-5) to discharge from the CPU (Day 9).

11. Use of study drug within 30 days prior to Day -5.

12. Positive virology (active hepatitis B [HBsAg], hepatitis C [HCV], or human immunodeficiency virus [HIV] infection), alcohol or drug abuse during screening.

13. Use of any prescribed medication within 7 days prior to admission to the CPU, or required chronic use of any prescribed or over-the-counter drug, except Hormone Replacement Therapy (HRT) for post-menopausal women and hormonal contraceptives.

14. History of tobacco use, alcohol abuse, illegal drug use, significant mental illness, physical dependence on any opioid, or any history of drug abuse or dependence within 12 months of study registration.

15. Has significant blood loss (> 450 ml) or donated 1 or more units of blood or plasma within 8 weeks prior to study entry.

Exclusion of patients from therapy or evaluation . Patients had the freedom to terminate the study at any time, for any reason, and without prejudice to further treatment. The investigator could exclude a patient if, in the judgment of the investigator, continued participation posed an unacceptable risk to the patient or to the integrity of the study data. Patients who dropped out of the study early could be replaced as agreed with the sponsor.

Performance Evaluation - Demographic and Other Basic Characteristics . All patients enrolled in the study were receiving study treatment and all had at least 1 postbaseline PD study.

A summary of the demographic characteristics of patients enrolled in the study, overall and by group, is provided in Table E8 below. Some variability was observed between groups (especially with respect to gender and race); however, the baseline characteristics of most groups reflected those of the entire population.

No clinically significant pathological findings were noted for any patient during the physical examination performed at screening.

Table E8
Demographic and baseline characteristics Parameter Group 1
30 mg twice a day
(n=12) Group 3
60 mg twice a day
(n=12) Group 4
15 mg twice a day
(n=12) Average (SD) 38.8 (16.49) 37.8 (11.78) 38.7 (12.91) Median 31.0 33.5 36.5 Min, max 20.63 22.61 20.60 female 3 (25.0) 3 (25.0) 2 (16.7) Male 9 (75.0) 9 (75.0) 10 (83.3) Average (SD) 73.7 (11.39) 79.3 (9.98) 78.7 (12.99) median 71.7 75.7 79.7 Min, max 58.91 67.103 60.101 Average (SD) 24.6 (2.69) 26.1 (2.46) 25.7 (2.87) median 24.3 26.2 25.9 Min, max 19.29 22.29 20.30 Asian 1 (8.3) 1 (8.3) 0 Black 2 (16.7) 6 (50.0) 4 (33.3) White 7 (58.3) 5 (41.7) 6 (50.0) Other 2 (16.7) 0 1 (8.3) Absent 0 0 1 (8.3)

The event pattern for screening and treatment period is shown in Table E9 below.

Table E9 Procedure Screening and base
Day Double-blind treatment period
Day Observation -26 - -5 -five ^a -four -3 -2 -1 1 2 3 four five 6 7 8 nine ^a 23 + 2 Informed Consent X Inclusion/exclusion X X ^b Anamnesis X X ^b Physical examination X Vital signs X X X X X X X X X X X X X X X ECG score X Lab Safety Rating X X Screening for alcohol/drugs X X FSH test X Pregnancy test X X Randomization X Dosing X X X X X X X 24 h urine/feces collection X X X X X X X X X X X X X Stool shape/time X X X X X X X X X X X X X Pharmacodynamic laboratory evaluation X X X X X AE rating X X X X X X X X X X

Medicine for research . Capsules with Comm. 002 or matching placebo capsules were administered with approximately 240 ml of 15 mg still water or placebo. Comm. 002 was an amorphous off-white powder and was used in the form of size 0 white hydroxypropyl methylcellulose (HPMC) capsules. Each capsule contained 15 mg Comp. 002. The capsules were packaged in cans of opaque white high density polyethylene (HDPE) (10/can). The drug product was formulated without excipients.

The placebo was in the form of size 0 white HPMC capsules filled with methylcellulose. The capsules were packaged in an opaque white HDPE can (10/can).

Method of allocation of patients to treatment groups . The study organization's clinical statistician prepared a randomization design in accordance with his standard operating procedures (SOP) and a randomization plan that reflected GCP standards.

After informed consent was obtained, patients were assigned sequentially to groups in their order of completion of screening studies.

Within each group, a computer-generated randomization plan was used to randomly allocate patients to active Comp. 002 or placebo in a ratio of 4:1.

Once a patient was deemed eligible for randomization, the next available randomization number was assigned sequentially and the patient received the treatment indicated on the randomization plan. Patients who withdrew from the study early could be replaced as agreed with the sponsor. Replacement patients received the same blind treatment as the original patient.

Choice and timing of administration for each patient . Patients were assigned sequentially to groups of 15 patients each in order of completion of screening studies and received either 002 or placebo based on random assignment. Table E10 shows the actual mode of administration for each group. Because this was an adaptive design protocol, the administration regimen for each group was based on the blinded results of previous groups.

Table E10
Administration mode for each group Group no. The patients ^a Dose/Administration Mode Total dose/day 1 15 30 mg Twice a day 60 mg 3 15 60 mg Twice a day 120 mg four 15 15 mg Twice a day 30 mg ^a Each group consisted of 12 patients administered Comp.002 and 3 patients administered placebo.

Doses were administered just before breakfast and lunch. Patients were not allowed to eat or drink anything from 8 hours prior to breakfast administration, except for water until 2 hours prior. Patients were fed a standardized diet approximately 10 minutes after administration.

The standardized diet included approximately 1500 mg Na ⁺ for each meal. Dietary phosphorus was not measured or limited to a predetermined value. It was expected to be within the typical range, ie 750 mg - 1250 mg per day.

Patients did not have access to salt to add to their meals. Fluid intake was ad libitum (and recorded) except as determined before drug administration. Patients were required to refrain from strenuous physical activity (eg, contact sports) during study participation.

Blind method . Treatment was applied in a double-blind manner. Only the pharmacist responsible for distributing the product and the laboratory technician of the bioanalytical laboratory responsible for performing the bioassay Comm. 002 in plasma had an idea of the prescribed treatment.

The study remained blind to safety reviews between groups.

The third party kept the randomization plan in a secure location with suitable controls to prevent unauthorized access.

One set of envelopes (sealed envelopes containing individual treatment prescriptions for patients) was stored at the CPU.

The study was only released when all data from the final group had been collected and the database was locked.

Prior and concomitant therapy . This was a study of healthy patients. Patients with prior therapy as defined in the exclusion criteria were not eligible for study entry.

With the exception of HRT for postmenopausal women and hormonal contraceptives, the use of concomitant medications was prohibited during the study unless necessary for the treatment of AE.

All previous medications (prescription and over-the-counter), vitamin and mineral supplements, and herbs taken by the participant in the past 30 days were recorded in CRF, including start and stop dates, dose and route of administration, frequency, and indications. Medications received for the procedure were also included.

Consent to treatment . All doses of drug for the study were given under the supervision of the clinic staff, and the time and dose administered were recorded in the CRF. The clinical staff examined the patient's mouth and hands after drug administration to ensure that the capsule(s) had been swallowed.

Efficiency Variables . The study consisted of a 3-week screening period followed by a 5-day baseline study, a 7-day double-blind treatment period with 2 days of follow-up for PD and safety studies. Fourteen days after the treatment period, patients were contacted by telephone for safety monitoring.

Patients were admitted to the CPU 5 days prior to the first dose of study drug and remained on the ward throughout the treatment period, discharged on Day 9.

Safety studies were carried out starting on Day -5 and included a physical assessment; vital signs; ECG with 12 electrodes; routine serological chemistry, hematology and urinalysis; and AE report. Pharmacodynamic studies were performed daily from Day -4 to Day 9 and included Na ⁺ excretion in urine and stool, time of first bowel movement, and stool parameters (consistency, mass, and frequency). Pharmacodynamic laboratory studies (plasma renin, aldosterone and NT-pRo BNP) were performed on Days -4, -1, 3, 6 and 9.

Laboratory Research . Blood and urine samples for clinical laboratory testing (hematology, chemistry, urinalysis) were collected during screening (to identify inclusion/exclusion criteria) and on Day -4 and Day 9 after waking up and before breakfast.

In addition, blood was collected at screening and on Day -5 for alcohol/drug screening, FSH test (only women after menopause), and pregnancy test (all women). Virological screening for HBsAg, HCV and HIV was performed at screening.

Pharmacodynamic variables . The following PD parameters have been tested as a signal of potential drug activity:

• Excretion of Na ⁺ in the stool

• Excretion of phosphorus in the stool

Bowel movements . The study participants were instructed to inform the research staff just prior to a bowel movement. Research staff recorded the time of each bowel movement and assessed stool parameters (eg, consistency, mass). Bowel movements that occurred prior to leaving the sanitary room were counted as 1 bowel movement. All faeces were collected, weighed and stored in the CPU for analysis of total Na ⁺ and P; cumulative data were for 24-hour intervals.

Pharmacodynamic studies - ways to analyze sodium and phosphorus in stool . Human faecal samples were treated with nitric acid to obtain a pre-digested sample prior to laboratory determination of sodium and phosphorus. The pre-digested sample was further digested in nitric acid at 100° C. followed by treatment with hydrochloric acid at 100° C. and diluted with demineralized water. Yttrium was added to the digested sample as an internal standard. Calibration standards and quality control samples were digested using the same procedure. Sodium and phosphorus concentrations were determined by inductively coupled plasma optical emission spectrometric method (ICP-OES). The light intensity of the analyte and yttrium was measured on SCD (matrix) detectors. Analyte-yttrium intensity ratios were converted to solution concentrations using software. The total content of sodium and phosphorus in each sample was calculated using the sample volumes obtained during the pre-digestion process and the concentrations were measured.

Results . After data discovery, pharmacodynamic measurements of P and Na in faeces and urine were performed in the placebo group (3 patients in each group × 3 groups = 9 patients) and in 3 treatment groups, respectively. The data is shown in Figures 14A-B . Figure 14A shows the average daily fecal excretion of Na (+/-SE) averaged over a 7-day treatment period (Day 1 - Day 7) and expressed as mEq/day. Figure 14B shows the mean daily fecal phosphorus excretion (+/-) averaged over a 7 day treatment period (Day 1 - Day 7) and expressed as mEq/day. Statistical analysis was performed by one-way ANOVA; (*); p<0.05, (**); p<0.01, (***); p < 001.

EXAMPLE 9

EVALUATION OF THE REDUCTION ACTIVITY OF DIETARY PHOSPHORUS AT A DOSE OF 15 MG TID IN A 7-DAY RE-DOSE CROSS STUDY IN HEALTHY VOLUNTEERS

A single-centre, randomized, 3-way, crossover, open Phase 1 study was designed to evaluate the pharmacodynamics of Comp. 002 for three different compositions Comm. 002 administered orally twice a day for 4 days in healthy male and female patients taking a proton pump inhibitor (omeprazole) using a tripartite crossover regimen. Many potential patients are taking either PPIs or H2 antagonists to treat gastroesophageal reflux (GERD). However, the dissolution profiles of Comm. 002 in vitro can be altered by high pH, at which slower and/or incomplete dissolution is sometimes observed. To assess the pharmacodynamic activity of the drug in the context of elevated gastric pH, patients in this study were required to be on omeprazole starting on Day -5 during the treatment period.

Patients were screened for 3 weeks prior to enrollment. Each patient received omeprazole 20 mg twice daily starting on Day -5. patients were registered at the Clinical Pharmacology Unit (CPU) on Day -2 before lunch. Each patient received a diet standardized for Na ⁺ content during their stay at the CPU. Patients received one of three formulations of Comm. 002 twice a day with approximately 240 ml of still water on Days 1 - 4, 7 - 10 and 13 - 16 (each time a different composition). Patients were fed breakfast and/or lunch for approximately 5 minutes after administration. There was a two day washout period between each treatment period.

While in the CPU, Na ⁺ -standardized nutrition was provided using CPU routines.

The pharmacodynamic study included a 24-hour measurement of sodium and phosphorus in urine and a measurement of sodium and phosphorus in feces.

At least 18 healthy male and female patients were randomized in this study.

Patient Selection Criteria - Inclusion Criteria.

1. Healthy male or female aged 19 - 65 years, inclusive.

2. Body mass index (BMI) from 18 to 29.9 kg/m ² inclusive.

3. Absence of clinically significant abnormalities on history, physical examination, or clinical laboratory evaluations at screening.

4. Ability to understand and follow protocol.

5. Willingness and ability to sign informed consent.

6. Women of childbearing age must have a negative pregnancy test at screening and on admission to the ward and must not be lactating.

7. Women of childbearing age included in the study must use two effective methods of preventing pregnancy (including oral, transdermal or implantable contraceptives, intrauterine device, female condom with spermicide, diaphragm with spermicide, cervical cap, or use of condom with spermicide by sexual partner) from from the time of screening until the follow-up visit.

8. Women of non-child-bearing age confirmed by screening must meet one of the following criteria:

a. Be in a period after menopause, defined as amenorrhea, for at least 12 months or more; subsequent cessation of all exogenous hormonal treatments and LH and FSH levels after menopause; or

b. Documentation of irreversible surgical sterilization by hysterectomy, bilateral oophorectomy, or bilateral salpingectomy, but not by tubal ligation.

9. Men were either infertile, abstaining, or willing to use, from enrollment to 45 days from final study visit, 1 of the following approved methods of contraception: male condom with spermicide; infertile sexual partner; use by a female sexual partner of a spermicide intrauterine device, spermicide female condom, spermicide sponge, intravaginal system (such as NuvAring®), spermicide diaphragm, spermicide cervical cap, or oral, implantable, transdermal, or injectable contraceptives.

10. To be included in an optional genetic study, patients must fulfill all of the inclusion criteria described above and provide informed consent for the collection and analysis of genetic samples.

Exclusion Criteria . Patients were excluded from the study if they met any of the following criteria:

I. Diagnosis or treatment of any clinically characteristic biochemical or structural abnormality of the gastrointestinal (GI) tract.

2. Any surgery to the small intestine or large intestine, excluding appendectomy or cholecystectomy, or any other condition known to interfere with the absorption, distribution, metabolism, or excretion of drugs.

3. Clinically evident presence of significant cardiovascular, respiratory, renal, hepatic, gastrointestinal, hematological, metabolic, endocrine, neurological, psychiatric disease, or any condition that could prevent the patient from successfully completing the test or that would result in a risk to patient safety .

4. History of severe allergy/hypersensitivity or ongoing allergy/hypersensitivity as assessed by the investigator, or history of allergy to drugs with a chemical structure or class similar to CPD002.

5. Frequent loose stools (Bristol Stool Scale 6 or 7) > 2 days in the past 7 days.

6. Hepatic dysfunction (alanine aminotransaminase [ALT] or aspartate aminotransaminase [AST]) > 1.5 times upper limit of normal [ULN]) or kidney damage (serum creatinine > ULN).

7. Clinically significant laboratory results at screening, as determined by the investigator.

8. Any demonstrable presence or treatment of malignant disease, excluding non-melanomatous skin malignancies.

9. If, in the opinion of the Investigator, the patient was unable or unwilling to comply with protocol requirements or had a condition that rendered the results uninterpretable.

10. Use of diuretics; treatments known to affect stool consistency and/or gastrointestinal motility, including fiber supplements (unless required for study), antidiarrheal drugs, laxatives, antacids, opiates, sleeping pills, prokinetic drugs, enemas , antibiotics, probiotic medicines or supplements; or salts or electrolyte supplements containing sodium, potassium, chloride, or bicarbonate formulations from CPU enrollment (Day -2) to CPU discharge (Day 17).

11. Use of study drug within 30 days prior to Day -2.

12. Positive virology (active hepatitis B infection, hepatitis C infection, or human immunodeficiency virus infection), alcohol or drug abuse during screening.

13. Use of any prescribed medication within 7 days prior to admission to the CPU, or required chronic use of any prescribed or over-the-counter drug, except hormone replacement therapy for postmenopausal women and hormonal contraceptives.

14. History of tobacco use, alcohol abuse, illegal drug use, significant mental illness, physical dependence on any opioid, or any history of drug abuse or dependence within 12 months of study registration.

15. Had significant blood loss (> 450 ml) or donated 1 or more units of blood or plasma within 8 weeks prior to study entry.

Medicine for research . Capsules Comp. 002 bis-HCl (eg dihydrochloride salt of Comp. 002), tablets Comp. 002 bis-HCl and tablets Comp. 002 in free base form. Comm. 002 bis-HCl salt is an amorphous off-white powder. Comm. 002 in free base form is a white crystalline solid. Comm. 002 is available as either a size 0 white HPMC (Hydroxypropyl Methylcellulose) capsule or a white round tablet. Capsules were prepared at a dosage of 15 mg, based on the molecular weight of Comm. 002 in the form of dihydrochloride, which are equivalent to 14 mg Comm. 002 in free base form. To ensure comparable dosages throughout this study, tablets of both compounds, the dihydrochloride salt and the free base, were given at dosages reflecting 14 mg as free base. The capsules and tablets were packaged in a white HDPE (high density polyethylene) can. Capsules and tablets Comm. 002 was kept refrigerated (2 to 8°C) in its original packaging until use. Tablet components are described below in Table E11 .

Table E11 Component free base dihydrochloride salt % form Weight/tablet (mg) % form Weight/tablet (mg) Comp.002 5.9 ^14.7a 6.4 ^15.9a Prosolv HD90 86.1 215.3 85.6 214.1 Polyplasdone XL 5.00 12.5 5.00 12.5 Mg stearate 2.00 5.0 2.00 5.0 cabosil 1.00 2.5 1.00 2.5 Total 100.00 250.0 100.00 250.0 a. Adjusted for purity, residual solvents, water content and inorganic content

Dose and route of administration . Capsules or tablets with Comm. 002, 15 mg (equivalents to 14 mg free base) was administered with approximately 240 ml of still water, twice a day orally before breakfast and lunch for 4 consecutive days during the treatment period, with a 2 day washout period between treatments. Omeprazole 20 mg was administered twice daily to screened patients starting on day -5. All patients received omeprazole 20 mg twice a day one hour before taking Comp. 002 each day until their last study drug dose on Day 16. See Table E12 , below.

Table E12 Treatment Patients ^a Dose/administration ^b Mode Composition 1 eighteen 15 mg Twice a day Capsule Comp.002 bis-HCl 2 eighteen 15 mg Twice a day Capsule Comp.002 bis-HCl 3 eighteen 15 mg Twice a day Tablet Comp.002 a. All patients received all three treatments; 6 patients/treatment period. There were two wash days between each treatment period.
b. Doses equivalent to Comp.002 free base (MW 1145.049)

Once a patient was deemed eligible for randomization, the next available randomization number was assigned sequentially and the patient received the treatment indicated on the randomization plan. All doses of drug for the study were given under the supervision of the clinic staff, the time and dose administered were recorded in the case history form (CRF). The clinic staff examined the patient's mouth and hands after drug administration to ensure that the capsule had been swallowed.

Fluid and food intake . Patients participating in the study were given a standardized diet with an approximate sodium content (approximately 1500 mg for each meal). Dietary phosphorus was not measured or limited to a predetermined value. It was expected to be within the typical range, ie 750 mg - 1250 mg per day. Patients did not have access to salt or any other sodium-containing spices or sauces to add to their meals.

Fluid intake was ad libitum, except as determined before drug administration. The daily menus (food and liquid) were similar during each treatment period.

Pharmacodynamic variables . The following parameters were tested as a signal of potential drug activity.

• urinary sodium excretion (daily)

• fecal sodium excretion (daily)

Bowel and urinary data were collected as previously described (Example 8); the pharmacodynamic activity of the three dosage forms was evaluated as follows. Baseline fecal phosphorus or sodium excretion was set as the average of daily fecal phosphorus or sodium excretion from Day -1 to Day 0, except for one patient for whom baseline was established during the first washout period, i.e., from Day 6 and Day 7. Daily fecal excretion of phosphorus or sodium after treatment was measured, constituting the average fecal excretion of phosphorus or sodium over the 4-day treatment period. The same method was used for urine.

Results . The results are shown in Figures 15A-C . Statistical analysis was performed by one-way ANOVA; (*); p<0.05, (**); p<0.01, (***); p < 001.

Figure 15A shows the average daily excretion of phosphorus (+/-SE). Baseline fecal excretion of phosphorus or sodium was set as the average of daily faecal excretion of phosphorus or sodium from Day -1 to Day 0, except for one patient for whom baseline was set during the first washout period, i.e. from Day 6 and Day 7 (referred to as "Predose"). Daily faecal excretion of phosphorus after treatment with 15 mg HCl tablet twice daily was measured, constituting the average faecal excretion of phosphorus or sodium over a 4-day treatment period.

Figure 15B shows the average daily urinary sodium excretion (+/-SE). Baseline fecal sodium excretion was set as the average of daily urinary sodium excretions from Day -1 to Day 0, except for one patient for whom baseline was set during the first washout period, that is, from Day 6 and Day 7 (called "Predose"). Daily urinary sodium excretion after treatment with the three forms of drug products was measured as the mean urinary sodium excretion over a 4-day treatment period.

Figure 15C shows mean daily urinary phosphorus excretion (+/-). Baseline fecal phosphorus excretion was set as the average of daily urinary phosphorus excretion from Day -1 to Day 0, except for one patient for whom baseline was set to during the first washout period, i.e. from Day 6 and Day 7 (referred to as "Predose"). The daily urinary phosphorus excretion after treatment with the three forms of drug products was measured, constituting the mean urinary phosphorus excretion over a 4-day treatment period.

EXAMPLE 10

EFFECT OF RENVELA® ON THE PHARMACODYNAMICS OF COMPOUND.002

A single-centre, randomized, open-label Phase 1 study was designed to evaluate the effect of Renvela® on the pharmacodynamic activity of Comp.002 in the form of the dihydrochloride salt (see Table E4) when administered twice a day orally for 4 days in healthy male and female patients. .

Patients were screened within 3 weeks of enrollment. Eighteen patients checked into the CPU on Day -2 before lunch. Each patient received a diet standardized for Na ⁺ content while in the CPU. Patients received Compound 002 15 mg twice daily on Days 1-4 and Days 7-10. Patients were fed breakfast and/or lunch for approximately 5 minutes after administration. During one of two treatment periods (randomly assigned), patients received one 800 mg Renvela® tablet with breakfast, breakfast, and lunch (Days 1-4 or Days 7-10). There was a two day washout period between each treatment period. During the stay in the CPU, Na ⁺ standardized meals were given using CPU procedures. The pharmacodynamic study included 24-hour measurements of sodium and phosphorus in the feces.

Patient selection criteria and study drug description were the same as described in Example 9 (above). The scheme of studies and procedures is shown below in Table E13 .

Table E13 Research procedure Screening Adaptation Treatment period 1 Washing/adapting Treatment period 2 Day -21 - -3 -2 -1 1 2 3 four five 6 7 8 nine 10 Introduction of Renvela® X X X X X X X X Introduction Conn.002 X X X X X X X X Urine/feces collection in 24 hours X X X X X X X X X X X Stool evaluation X X X X X X X X X X X X Taking a blood sample for PK X X

Pharmacodynamic variables . Baseline fecal excretion of phosphorus or sodium was set as the average of daily fecal excretion of phosphorus or sodium from Day -1 to Day 0. Daily faecal excretion of phosphorus or sodium after treatment was measured as the mean fecal excretion of phosphorus or sodium over the 4-day treatment period. . Analytical methods for sodium and phosphorus were performed as described in Example 8 (above).

Results . The data is shown in Figures 16A-B . Statistical analysis performed by one-way ANOVA followed by Tukey's multiple comparison test; (*); p<0.05, (**); p<0.01, (***); p < 0.001 vs. predose.

Mean daily fecal sodium excretion (+/-SE) is shown in Figure 16A . Here, the basal fecal excretion of sodium was set as the average of the daily fecal excretion of phosphorus or sodium during Day -1 to Day 0 (called "Predose"). Daily fecal sodium excretion after treatment with a bis-HCl 15 mg tablet twice daily was measured to give an average fecal sodium excretion over a 4-day treatment period.

Average daily fecal phosphorus excretion (+/-SE) is shown in Figure 16B . Baseline fecal phosphorus excretion was set as the average of daily fecal phosphorus excretion during Day -1 to Day 0, (called "Predose"). Daily fecal phosphorus excretion following treatment with a 15 mg bis-HCl tablet twice daily was measured to give the mean fecal phosphorus excretion over a 4-day treatment period.

Claims (84)

1. A method for inhibiting phosphate uptake in the gastrointestinal tract of a patient in need of lowering phosphate levels, comprising enterally administering to the patient an effective amount of an NHE3 inhibitor. 2. The method of claim 1 wherein the NHE3 inhibitor is substantially systemically non-bioavailable. 3. The method of claim 1 wherein the NHE3 inhibitor is a compound of Formula (X)

wherein NHE is

L is a polyalkylene glycol linker; n = 2; and Core (central part) is selected from:

or a pharmaceutically acceptable salt thereof. 4. The method of claim 3 wherein the polyalkylene glycol linker is polyethylene glycol. 5. The method according to any one of paragraphs. 1-4, further comprising administering to the patient an additional biologically active agent. 6. The method of claim 5 wherein the additional biologically active agent is a phosphate binder. 7. The method of claim 5 wherein the additional biologically active agent is selected from the group consisting of sevelamer, sevelamer carbonate, sevelamer hydrochloride, lanthanum carbonate, calcium carbonate, calcium acetate, magnesium carbonate, MCI-196, iron citrate, magnesium hydroxycarbonate- iron, alumina hydrate, APS 1585, SBR-759 and PA-21. 8. The method of claim 5 wherein the additional biologically active agent is selected from the group consisting of sevelamer carbonate, lanthanum carbonate, calcium carbonate, calcium acetate, calcium acetate/magnesium carbonate, iron citrate, magnesium iron hydroxycarbonate and aluminum hydroxide. 9. The method of claim 6 wherein the phosphate binder is sevelamer, sevelamer carbonate or sevelamer hydrochloride. 10. A method of treating hyperphosphatemia in a patient in need thereof, comprising administering to the patient an effective amount of an NHE3 inhibitor. 11. The method of claim 10, wherein the NHE3 inhibitor is substantially systemically non-bioavailable. 12. The method of claim 10 or 11 wherein the NHE3 inhibitor is a compound of Formula (X)

wherein NHE is

L is a polyalkylene glycol linker; n = 2; and Core (central part) is selected from:

or a pharmaceutically acceptable salt thereof. 13. The method of claim 12 wherein the polyalkylene glycol linker is polyethylene glycol. 14. The method according to any one of paragraphs. 10-13, further comprising administering to the patient an additional biologically active agent. 15. The method of claim 14 wherein the additional biologically active agent is a phosphate binder. 16. The method of claim 14 wherein the additional biologically active agent is selected from the group consisting of sevelamer, sevelamer carbonate, sevelamer hydrochloride, lanthanum carbonate, calcium carbonate, calcium acetate, magnesium carbonate, MCI-196, iron citrate, magnesium hydroxycarbonate- iron, alumina hydrate, APS 1585, SBR-759 and PA-21. 17. The method of claim 14 wherein the additional biologically active agent is selected from the group consisting of sevelamer carbonate, lanthanum carbonate, calcium carbonate, calcium acetate, calcium acetate/magnesium carbonate, iron citrate, magnesium iron hydroxycarbonate and aluminum hydroxide. 18. The method of claim 15 wherein the phosphate binder is sevelamer, sevelamer carbonate or sevelamer hydrochloride. 19. The method according to any one of paragraphs. 10-18, wherein the hyperphosphatemia is postprandial hyperphosphatemia. 20. The use of an NHE3 inhibitor in the manufacture of a medicament for inhibiting gastrointestinal phosphate uptake in a patient in need of lowering phosphate levels, the inhibition of gastrointestinal phosphate uptake comprising enterally administering the drug to the patient. 21. Use according to claim 20 wherein the NHE3 inhibitor is a compound of Formula (X)

wherein NHE is

L is a polyalkylene glycol linker; n = 2; and Core (central part) is selected from:

or a pharmaceutically acceptable salt thereof. 22. Use of an NHE3 inhibitor in the manufacture of a medicament for the treatment of hyperphosphatemia in a patient. 23. Use according to claim 22 wherein the NHE3 inhibitor is a compound of Formula (X)

wherein NHE is

L is a polyalkylene glycol linker; n = 2; and Core (central part) is selected from:

or a pharmaceutically acceptable salt thereof. 24. The method according to any one of paragraphs. 1, 2, 10 and 11 or the use of claim 20 or 22 wherein the NHE3 inhibitor is a compound of Formula (X)

wherein n = 2; L is a polyalkylene glycol linker; Core (central part) is selected from the group consisting of:

each NHE represents

each B is a guanidinyl bioisostere; X is a bond; and each Scaffold is an NHE inhibitory small molecule

25. The method or use of claim 24, wherein Core is selected from the group consisting of:

26. The method or use according to claim 24 or 25, wherein L is

where x is 2, 3 or 4. 27. The method or application according to any one of paragraphs. 24-26 where x is 2. 28. The method or application according to any one of paragraphs. 24-27 where each Scaffold is an NHE inhibitory small molecule

29. The method of claim 24, wherein the NHE3 inhibitor has the structure

30. The method or application according to any one of paragraphs. 24-29, where B is a 5-membered ring. 31. The method or application according to any one of paragraphs. 24-29, where B is a 6-membered ring.

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