OA11781A - Dry powder active agent pulmonary delivery. - Google Patents

Abstract

The present invention is directed to particulate compositions and methods for delivering an active agent to the lung of a human patient. The active agent formulation is in dry powder form and exhibits (i) low moisture sorption, and (ii) a resistance to hygrosscopic growth, particularly under simulated lung conditions.

Description

DRY POWDER ACTIVE AGENT PULMONARY DELIVERY

Field of the Invention

The présent invention is related to the improved delivery of a dry powderactive agent formulation to the deep lung. More particularly, the invention is directed 5 to aerosolizable dry powder particles, which, upon inhalation, are résistant to hygroscopic growth. This feature of the powder (i.e., hygroscopic growth résistance)permits a greater proportion of the inhaled particles to reach the deep lung, therebyincreasing the bioavailability of an active agent that is delivered to the lung.

Background of the Invention 10 Pulmonary delivery of active agents has been shown to be an effective route of administration for both local and systemic drug applications. Pulmonary active agentformulations are designed to be delivered via inhalation by the patient of a drugdispersion so that the active agent within the dispersion can reach the lung. It hasbeen found that certain drugs delivered to the lung are readily absorbed through the 15 alveolar région directly into the blood circulation. However, the percentage of inhaleddrug that actually reaches the deep lung is quite small. For pulmonary delivery, druglosses average about 30% to the device, and about 35% to the oropharanx (upperairways). Out of the remaining 35%, about 20% drug is lost to the conductingairways, while about 15% is absorbed in the alveolar région. As pointed out by 20 Gonda et al, Critical Reviews in Therapeutic Drug Carrier Systems, Volume 6, Issue4 (1990) pages 273-313, absorption of drug in the distal airways and alveoli isexpected to be faster than in the upper airways since the diffusion barriers are thinnerand the surface area is greater in those régions. However, since only a small fractionof inhaled drug actually reaches the alveolar surface, new approaches are needed for 25 increasing the amount of drug that ultimately reaches the systemic circulation. 1 117ο :

In one approach to solving this problem, Backstrom et al, U.S. Patent No.5,506,203 describes the use of perméation enhancers to increase absorption throughthe laver of épithélial cells in the lower respiratory tract, thereby ultimately increasingthe amount of drug reaching the systemic circulation. The inhaled compounds of 5 Backstrom are delivered in the form of particles with a diameter of less than 10 microns. Perméation enhancers employed include surfactants, salts of fatty acids, bile —salts and their dérivatives, and others. Wong et al, U.S. Patent No. 5,451,569similarly describes the use of lung surfactant to enhance the pulmonary absorption ofproteins and peptides. 10 In an effort to eliminate the need for perméation enhancers, International

Publication WO 96/32149, assigned to Inhale Therapeutic Systems, describes thepulmonary delivery of aerosolized médicaments that are in dry powder fonn and aredispersible. Such médicaments are readily absorbed in the lungs without the need toemploy perméation enhancers. Similar efforts to increase the bioavailability of 15 inhaled drugs are described in International Publication WO 97/44013, assigned toMIT and Penn State. In this publication, aerodynamically light particles (havingdensities less than 0.4 grams/cm3 with a large mean diameter greater than 5 microns)are used for enhanced delivery of a therapeutic or diagnostic agent to the alveolarrégion of the lung. To further enhance drug bioavailability, International Publication 20 WO 98//31346, also assigned to MIT and Penn State, discloses the incorporation ofsurfactant into the aerodynamically light particles for promoting absorption of theagent and for increasing its bioavailability. "

Besides the problem of low absorption of pulmonarily delivered active agentsthrough the épithélial cells in the lower respiratory tract, another factor contributing to 25 the small quantities of inhaled drug reaching the deep lung is hygroscopic growth.

Due to their water-soluble nature, most aérosols bring about the increased dépositionof particles in the upper respiratory tract as a resuit of hygroscopic growth (Hickey, etal, Journal of Pharmaceutical Sciences, Volume 79, Number 11, pages 1009-1014).

To investigate the growth rate of powders in humid environments, powders of 30 disodium fluorescein coated with a fatty acid were prepared by an adsorption coacervation technique. The coated powders possessed MMAD’s between about 4 117 8 1 and 7 microns and showed a reduced growth rate when compared to uncoatedpowders.

In spite of many of the above approaches, the percentage of drug generallyreaching the alveolar surface of the Iung upon inhalation is still quite low. Thus, newand improved efforts are needed for increasing the amount of inhaled drug depositedin the deep lung, to thereby increase the bioavailability of inhaled active agents.

Summary of the Invention

It is not onîy the size and density of the particles that are important parametersfor increased bioavailability of drugs delivered to the alveolar région of the lung, butalso their ability to absorb water as they travel through the lung to the alveoli. Wehâve discovered that merely coating a particle is not sufficient to minimize absorptionof water in the lung, rather the entire particle must contain hygroscopic growthinhibiting properties in order to maintain an appropriate particle size distribution inthe aérosol as it travels through the lung, to enable its passage, without priordéposition in the upper lung régions, to the alveolar surface.

Accordingly, in one aspect, the invention is directed to particles for delivery ofan active agent to the alveoli of a human patient. The particles comprise the activeagent and a hygroscopic growth inhibitor. The hygroscopic growth inhibitor isincorporated within the particles and the particles maintain an aérosol particle sizedistribution below 3 microns MMAD when delivered to the alveoli.

In another aspect, the invention is directed to particles containing an activeagent and a hygroscopic growth inhibitor, where the particles are highly dispersible,and exhibit a drop in emitted dose under simulated lung conditions of no more thanabout 25%.

According to yet another aspect, the invention is directed to particles havinglow moisture absorptivities. The particles contain an active agent and a hygroscopicgrowth inhibitor, and are further characterized by a sorption index of less than about6.5. 14 ' Λ 4 ' I ί ο » 4k "

In another aspect, the présent invention is directed to a method for preparingparticles for delivering an active agent to the alveoli of a human patient. The methodcomprises preparing a mixture of a hygroscopic growth inhibitor, an active agent anda solvent. The mixture is then spray dried to obtain homogenous particles of the 5 hygroscopic growth inhibitor and the active agent. The particle size distribution of theresulting particles remains less than 3 microns MMAD when delivered via inhalation _to the deep lung. Altematively, the resulting particles are characterized by exhibitinga drop in emitted dose of no more than 25% under simulated lung conditions. In yetanother alternative, the spray-dried particles are characterized by a moisture sorption 10 index of less than about 6.5

In yet another aspect, the invention is directed to a method for delivery of anactive agent to the lungs of a human patient, where aerosolized particles having theabove described features are administered by inhalation to a human patient.

Another aspect of the invention is directed to a method for increasing the15 quantity of an inhaled active agent deposited in the deep lung. The method involves incorporating into active agent-containing dry powder particles for inhalation, ahygroscopic growth inhibiting agent, such that, upon aerosolization and inhalation ofthe particles, at least 20% of the nominal dose is deposited in the deep lung.

These and other objects and features of the invention will become more fully20 apparent when the following detailed description is read in conjunction with the accompanying figures and examples.

Brief Description of the Figures

Fig. 1 shows moisture sorption profiles of various spray-dried powder25 formulations, with moisture uptake (% by weight) on the vertical axis and % relative humidity on the horizontal axis. (Circles·. 20% insulin, 59% sodium citrate, 18%mannitol, 2.6 glycine: Squares·. 100%dextran(10K); Diamonds'. 100%hydroxypropylmethylcellulose; £_ 100% hydroxypropyl-P-cyclodextrin, and +: 100%low molecular weight hydroxyethylstarch); .1178 1

A

Fig. 2 shows moisture sorption profiles for 3 different spray-dried powderformulations. (Circles·. 20% insulin, 59% sodium citrate, 18% mannitol, 2.6 glycine;Squares·. 20% insulin, 2.6% glycine, 40% hydroxyethylstarch, 18% mannitol, 19%sodium citrate; and Diamonds: 100% hydroxyethylstarch). The addition of one or moreHGIs to a particular formulation reduces its moisture sorption.

Fig. 3 shows the TAM (thermal activity monitor) results for various insulin drypowder formulations, illustrating the efficiency of two exemplary hygroscopic growthinhibiting agents in significantly reducing the hydration properties of these powders;

Fig. 4 is a moisture sorption plot for three spray-dried formulations, illustratingthe effectiveness of hygroscopic growth inhibiting agent-containing formulations indecreasing both the rate and overall extent of water uptake. (Circles·. 20% insulin, 59%sodium citrate, 18% mannitol, 2.6 glycine; Squares·. 100% spray-dried hydroxypropyl-β-cyclodextrin, and Diamonds·. 20% insulin, 20% leucine, 50% β-cyclodextrinsulfonylbutyl ether, 10% sodium citrate; and

Fig. 5 is a moisture sorption plot comparing 5 different spray-driedformulations. The plot further illustrâtes the ability of HGI-containing formulations tosignificantly reduce the rate and extent of water uptake when compared to non-HGIcontaining formulations. (Circles·. 20% insulin, 20% leucine, 50% hydroxyethylstarch,10% sodium citrate; Squares·. 20% insulin, 5% leucine, 50% hydroxyethylstarch, 25%sodium citrate: Diamonds·. 100% hydroxyethylstarch; X: : 20% insulin, 59% sodiumcitrate, 18% mannitol, 2.6 glycine; +; 20% leucine, 50% hydroxyethylstarch, 30%sodium citrate). . - ·

Detailed Description of the InventionThe présent invention provides a particulate composition and method for the pulmonaiy delivery of particles composed of an active agent and a hygroscopicgrowth inhibiting agent, where the particle size distribution of the particles is less than3 microns MMAD when delivered to the alveoli. The invention is surprising in that itprovides for increased bioavailability of the active agent over active agent particlesabsent the hygroscopic growth inhibiting agent or having the hygroscopic growthinhibiting agent solely adsorbed to their surface. It is thought that by having the 11 7« 1 hygroscopic growth inhibiting agent distributed throughout the particles rather thanprésent just as a coating on the surface, as the surface of the particles are eroded ordissolved during their passage through the airways, new internai layers of thehygroscopic growth inhibiting agent are exposed. thus providing to the particles a new 5 layer of hygroscopic growth inhibiting capability. I. Définitions

The following ternis as used herein hâve the meanings indicated. “Active agent” as described herein includes an agent, drug, compound, 10 composition of matter or mixture which provides some pharmacologie, often bénéficiai, effect that can be demonstrated in-vivo or in vitro. This includes foods,food suppléments, nutrients, drugs, vaccines, vitamins, and other bénéficiai agents.

As used herein, the terms further include any physiologically or pharmacologicallyactive substance that produces a localized or systemic effect in a patient. 15 “Dry powder” refers to a powder composition that contains finely dispersed solid particles that are free flowing and capable of (i) being readily dispersed in aninhalation device and (ii) inhaled by a subject so that a portion of the particles reachthe lungs to permit pénétration into the alveoli. Such a powder is considered to be“respirable” or suitable for pulmonary delivery. A dry powder typically contains less 20 than about 10% moisture, preferably less than 5% moisture, and more preferablycontains less than about 3% moisture. “Hygroscopic growth inhibitor, (HGI)”, means any material that, whenincorporated into the particles of the invention, reduces the rate and/or extent of wateruptake. Materials suitable for use as a hygroscopic growth inhibitor are effective, 25 when incorporated into the particles of the invention at a suitable concentration, toinhibit the hygroscopic growth of the particles under conditions typically found in thelung by at least 5%, preferably by at least 10%, and more preferably by at least 15%,when compared to particles having the same relative amounts of particle components,absent the HGI. 30 The hygroscopic growth of the particles is generally described in terms of a hygroscopic growth ratio, that is, the ratio of the MMAD of the particles under 117 5 1 conditions typicaliy found in the lung to the MMAD of the dry particles prior toinhalation. As an illustration, a particle having a hygroscopic growth ratio of 1 doesnot change size upon inhalation and exposure to the environmental conditions of thelung. The hygroscopic growth of particles is determined experimental] y by treatingthe powders in an environmental chamber simulating the conditions of the lung, i.e.,32-37°C and 95-99.5% relative humidity. More specifically, a dose of the particles is_aerosolized in a growth chamber as described above. The aérosol is then passed into acascade impactor, to détermine the mass médian aerodynamic diameter of theparticles.

Altematively, one can calculate the MMAD of a particular powdercomposition under simulated lung conditions to détermine the equilibrium growthratio. The MMAD of an aerosolized powder particle in the lung is determined bycalculating the solids concentration (powder to water ratio) at which an aqueoussolution of the powder becomes isotonie, i.e., the concentration at which a liquiddroplet reaches equilibrium in the lung, which then allows calculation of the MMADof the isotonie droplet. The MMAD of the isotonie droplet is then divided by theexperimentally determined MMAD of the powder under ambient conditions to obtainthe hygroscopic growth ratio.

Particles incorporating a HGI and having an MMAD below 3 microns undersimulated lung conditions as described above are encompassed by the présentinvention. “Simulated lung conditions” are 32-37°C and 95-99.5% relative humidity. “Sorption Index” or “SI” is the sum of the percent weight gain of a dry powderof the invention determined at 10%, 20%, 30% and 40% relative humidity (25 °C),divided by four. The sorption index is determined using a gravimétrie sorptionanalyzer, such as the DVS-1000, manufactured by Moisture Measurements System(London, UK) or moisture balance, manufactured by VTI Corporation (Hialeah, FL). “Particles of active agent” means the active agent as defined above in theform of particles that are süitable for pulmonary delivery. The particles form a drypowder. It is to be understood that more than one active agent may be incorporated 14 "*s 1 / ο*·ι into the aerosolized active agent formulation and that the use of the term “agent” in ifoway excludes the use of two or more such agents.

Particles having a hygroscopic growth inhibitor “incorporated “ within arethose particles having the HGI distributed throughout the particle, rather than présentsolely as a coating on the surface.

By “in-lung pulmonary bioavailability” is meant the amount of active agentwhich, after déposition in the lungs, is absorbed and becomes available in thesystemic circulation of a mammal relative to the amount that is absorbed into theblood from a subcutaneous injection site (% absorbed/ % deposited) relative tosubcutaneous). Représentative model Systems for determining in-lungbioavailibilities include rat, dog, and non-human primates. Relative in-iungpulmonary bioavailibilities may be based upon direct intratracheal administration orby inhalation. “Emitted Dose” or “ED” provides an indication of the distribution of drypowder within a suitable inhaler device after a firing or dispersion event. ED isdefîned as the ratio of the emitted dose to the nominal dose (i.e., the mass of powderper unit dose placed into a suitable inhaler device prior to firing). The ED is anexperimentally-determined parameter, and is typically determined using an in-vitrodevice set up which mimics patient-dosing. To détermine an ED value, a nominaldose of dry powder is placed into a suitable dry powder inhaler, which is thenactuated, dispersing the powder. The resulting aérosol cloud is then drawn by vacuumfrom the device, where it is captured on a tared filter attached to the devicemouthpiece. The amount of powder that reaches the filter constitutes the emitteddose. For example, for a 5 mg, dry powder-containing dosage form placed into aninhalation device, if dispersion of the powder results in the recovery of 4 mg ofpowder on a tared filter as described above, then the emitted dose for the dry powdercomposition is: 4 mg (emitted dose)/5 mg (nominal dose) x 100 = 80%. For non-homogenous powders, ED values provide an indication of the distribution of drugwithin an inhaler device after firing rather than of dry powder, and are based on drugweight rather than on total powder weight. 1178.1 “Drop in emitted dose under simulated lung conditions” means the ED valueunder ambient conditions (%) minus the ED value at 32-37 °C and 95-99.5% relativehumi'dity. A “dispersible” powder is one having a ED value of at least about 30%, morepreferably 40-50%, and even more preferably at least about 50-60%. “Mass médian diameter” or “MMD” is a measure of mean particle size, since-the powders of the invention are generally polydisperse (z.e., consist of a range ofparticle sizes). MMD values as reported herein are determined by centrifugalsédimentation, although any number of commonly employed techniques can be usedfor measuring mean particle size (e.g., électron microscopy, light scattering, laserdiffraction). “Mass médian aerodynamic diameter” or “MMAD” is a measure of theaerodynamic size of a dispersed particle. The aerodynamic diameter is used todescribe an aerosolized powder in terms of its settling behavior, and is the diameter ofa unit density sphere having the same settling velocity, in air, as the particle. Theaerodynamic diameter encompasses particle shape, density and physical size of aparticle. As used herein, MMAD refers to the midpoint or médian of the aerodynamicparticle size distribution of an aerosolized powder determined by cascade impaction,unless otherwise indicated. “Pharmaceutically acceptable excipient or carrier” refers to an excipient thatmay be included in the particles of the invention and taken into the lungs inassociation with the particles with no significant adverse toxicological efïects to thesubject, and particularly to the lungs of the subject. “Pharmacologically effective amount” or “physiologically effective amount ofa bioactive agent” is the amount of an active agent présent in a particulate dry powdercomposition as described herein that is needed to provide a desired level of bioactiveagent in the bloodstream of a subject to be treated to give an anticipated physiologicalresponse when such composition is administered pulmonarily. The précisé amount willdépend upon numerous factors, e.g., the bioactive agent, the spécifie activity of thecomposition, the delivery device employed, physical characteristics of the powder, its 11 , s 1 intended use, and patient considérations, and can readily be determined by one skilled inthe art, based upon the information provided herein. II. Components of the Inhalable Powder

The particles of the présent invention are designed to resist the hygroscopicgrowth which normally occurs upon pulmonary administration of dry powderformulations, to thereby enable a greater proportion of the inhaled particles to reachthe deep lung. This feature of the particles, i.e., résistance to hygroscopic growth, isachieved by the incorporation of a hygroscopic growth inhibiting agent, i.e., an agentwhose presence within the particles is effective to reduce the rate and/or extent ofwater uptake by the particles, particularly when exposed to the environmentalconditions of the lung. A. Active Agent

The active agent for incorporation in the particulate compositions describedherein include antibiotics, antiviral agents, anepileptics, analgésies, anti-inflammatoryagents and bronchodilators. The active agent may be an inorganic or organiccompound, including, without limitation, drugs which act on the peripheral nerves,adrenergic recep tors, cholinergic recep tors, the skeletal muscles, the cardiovascularSystem, smooth muscles, the blood circulatory System, synoptic sites, neuroeffectorjunctional sites, endocrine and hormone Systems, the immunological System, thereproductive System, the skeletal System, autacoid Systems, the alimentary andexcretory Systems, the histamine System the central nervous System. Suitable agentsmay be selected from, for example, polysaccharides, steroids, hypnotics and sédatives,psychic energizers, tranquilizers, anticonvulsants, muscle relaxants, antiparkinsonagents, analgésies, anti-inflammatories, muscle contractants, antimicrobiais,antimalarials, hormonal agents including contraceptives, sympathomimetics,polypeptides, and proteins capable of eliciting physiological effects, diuretics, lipidregulating agents, antiandrogenic agents, antiparasitics, neoplastics, antineoplastics,hypoglycémies, nutritional agents and suppléments, growth suppléments, fats,antienteritis agents, electrolytes, vaccines and diagnostic agents. 10

Examples of active agents suitable for use in this invention include but are notlimited to calcitonin, erythropoietin (EPO), Factor VIII, Factor IX, ceredase,cerezyme, cyciosporin, granulocyte colony stimulating factor (GCSF), alpha-1protéinase inhibitor, elcatonin, granulocyte macrophage colony stimulating factor(GMCSF), growth honnone, human growth hormone (HGH), growth hormonereleasing hormone (GHRH), heparin, low molecular weight heparin (LMWH), __interferon alpha, interferon beta, interferon gamma, interleukin-2, Iuteinizing hormonereleasing hormone (LHRH), insulin, somatostatin, somatostatin analogs includingoctreotide, vasopressin analog, follicle stimulating hormone (FSH), insulin-likegrowth factor, insulintropin, interleukin-1 receptor antagonist, interleukin-3,interleukin-4, interleukin-6, macrophage colony stimulating factor (M-CSF), nervegrowth factor, parathyroid honnone (PTH), thymosin alpha 1, Ilb/IIIa inhibitor, alpha-1 antitrypsin, VLA-4, respiratory syncytial virus antibody, cystic fibrosistransmembrane regulator (CFTR) gene, deoxyreibonuclease (Dnase),bactericidal/permeability increasing protein (BPI), anti-CMV antibody, interleukin-1receptor, 13-cis retinoic acid, pentamidine isethiouate, albuterol sulfate,metaproterenol sulfate, beclomethasone diprepionate, triamcinolone acetamide,budesonide acetonide, fluticasone, ipratropium bromide, flunisolide, cromolynsodium, ergotamine tartrate and the analogues, agonists and antagonists of the above.Active agents may further comprise nucleic acids, présent as bare nucleic acidmolécules, viral vectors, associated viral particles, plasmid DNA or RNA or othernucleic acid constructions of a type suitable for transfection or transformation of cells,particularly cells of the alveolar région of the lungs. The active agents may be invarious forms, such as water soluble or insoluble, charged or uncharged molécules,components of molecular complexes or pharmacologically acceptable salts. Theactive agents may be naturally occurring molécules or they may be recombinantlyproduced, or they may be analogs of the naturally occurring or recombinantlyproduced proteins with one or more amino acids added or deleted. Further, the activeagent may comprise live attenuated or killed viruses suitable for use as vaccines.

The amount of active agent in the aerosolized particles will be that amountnecessary to deliver a therapeutically effective amount of the active agent per unit il dose to achieve the desired resuit. In practice, this will vary widely depending uponthe particular agent, its bioactivity, the severity of the condition to be treated, thepatient population, dosing requirements, and the desired therapeutic effect. Theparticles will generally contain anywhere from 1% by weight to about 99% by weightactive agent, typically from about 2% to about 95% by weight active agent, and moretypically from about 5% to 85% by weight active agent. However, the particles are _particularly useful for active agents that must be delivered in doses of from 0.001mg/day to 100 mg/day, preferably 0.01 mg/day to 50 mg/day. B. Hvgroscopic Growth Inhibitor

An essential feature of the particles is the hygroscopic growth inhibitor. Thehygroscopïc growth inhibitor (HGI) is effective to reduce the rate and/or extent towhich moisture is absorbed by the particles upon inhalation, so that the particlesmaintain an MMAD of less than 3 microns upon delivery to the alveoli. A material suitable for use as an HGI is fîrst identified by a preliminaryscreening to détermine its moisture absorptivity profile after spray-drying; lowabsorptive materials are those preferred for use in the présent invention, such as thosematerials in Fig. 1. Those HGI materials are then further tested for suitability bypreparing particles containing anjppropriate amount of the HGI (typically greaterthan about 5 to 10 percent by weight of the composition). In some cases, the HGImay, in addition to being présent as part of the bulk powder, also form an additionalcoating on the surface of the particles. Moisture isotheims are then determined foractive agent particles containing the HGI and for control particles having the samerelative amounts of components absent the HGI, to détermine whether the presence ofthe HGI is effective to reduce either the extent or rate of water absorption by thepowder. Typically, both high and low concentrations of HGI are tested, to déterminethe useful ranges for incorporation into the powders of the invention.

Materials found to be useful as hygroscopic growth inhibitors include, but arenot limited to the following: double chain phospholipids, cyclodextrins and theirdérivatives, hydroxyethylstarch (HES), dextran, dextranomer, maltodextrins, starches,hydroxypropylmethylcellulose (HPMC), cellulose ethyl hydroxyethyl ether, and other 12

11 cellulose dérivatives, such as those described in “Cellulosics : Chemical, Biochemicaland Material Aspects” (Ellis Horwood Sériés in Polymer Science and Technology) byJ.F., B.Sc. Kennedy, G.O., B.Sc. Phillips, P.A. Williams (Editor), and in“Comprehensive Cellulose Chemistry” by D. Klemm (Editor), Bertram Philipp, T. 5 Heinze (1998). In some instances, the active agent may also function as a hygroscopic growth inhibiting agent. Active agents which tend to act as HGIs includeinsulin, salmon calcitonin, and PTH.

Double chain phospholipids for use in the présent invention includephosphatidylcholines such as l,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 10 l,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), l,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)- l,2-dioleoyl-sn-glycero-3-phosphochoIine (DOPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphochoIine (POPC), and the like. Also suitablefor use as a hygroscopic growth inhibitor are phophatidylethanolamines such as 1,2-dimyristoyl-sn-glycero-3-phosphoethanoîamine (DMPE), 1,2-dialmitoyl-sn-glycero- 15 3-phosphoethanolamine (DPPE), l,2-distearoyl-sn-glycero-3-phosphoethanolamine(DSPE), l,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), and similarlyderivatized phosphatidylglycerols and phosphatidic acids.

Cyclodextrins are another class of compounds found to be useful ashygroscopic growth inhibitors. Cyclodextrins, cyclic oligosacchrides shaped like a 20 truncated cône and having a hydrophobie cavity in center, are composed of more thansix D-glucose residues. Cyclodextrins for use in the présent invention include alpha-cyciodextrin (six glucose residues), beta-ryclodextrin, (seven glucose residues), andgamma-cyclodextrin (eight glucose residues) according to the number of glucoseresidues, respectively, as well as dérivatives, such as 2-hydroxypropyl-P-cyclodextrin 25 (2-HPpC) and β-cyclodextrin sulfonylbutyl ether. 2-ΗΡβΟ is a particularly preferredexcipient, as illustrated by its moisture sorption profile (Fig. 1). Ata target relativehumidity of 80%, 2-ΗΡβΟ exhibited a change of mass of only about 16% due to wateruptake, over a course of about 8 hours. Cyclodextrin exhibits a similar profile. Thebénéficiai moisture sorption properties of an exemplary formulation containing 30 sulfobutylether- β-cyclodextrin (2-SBEbC) are shown in Fig. 4. Thus, these materials 13 117 8 1 (i) are quite résistant to water uptake, and (ii) exhibit a slow rate of water uptake,making them suitable materials for incorporation in the powders of the invention.

Also useful as hygroscopic growth inhibiting agents are dextrans, which arepolysaccharides containing glucose monomers. Dextrans for use in the présentinvention possess a molecular weight ranging between about 10,000-100,000.Preferred are dextran 10, dextran 40, dextran 70, and dextran 75. Dextran derivatives-such as dextranomer (dextran 2,3-dihydroxypropyl 2-hydroxy-l,3-propanediyleithers), maltodextran and dextran sulfate sodium may also be used. Dextran’srésistance to moisture uptake was illustrated in a moisture sorption balanceexperiment, where it was shown that at 70% relative humidity, spray-dried dextranabsorbed only 19% water, while at 80% relative humidity, dextran exhibited a watersorption of 24% by weight, as illustrated in Example 3 and shown in Fig. 1.

Derivatized celluloses such as hydroxypropyl methylcellulose (HPMC),cellulose ethyl hydroxyethyl ether and hydroxypropyl cellulose, with molecularweights ranging fforn 10,000 to 400,000, are also useful as hygroscopic growthinhibitors.

Derivatized starches may also be employed as hygroscopic growth inhibitors.One particularly preferred hygroscopic growth inhibitor is hydroxyethylstarch (HES)having a molecular weight range front about 70,000 to about 400,000 (see, e.g., Fig. 2). A review of HES can be found in Intensive Care Med (1999) 25:258-268.

Also suitable for use as a hygroscopic growth inhibitor is maltodextrin, ahydrolyzed starch, and its commercially available dérivatives. Preferred isMaltodextrin 40, having an average molecular weight of about 3600.

An HGI useful in the particles and methods of the invention will combineeffective minimization of hygroscopic growth with (1) lack of toxicity in theconcentrations used and (2) good powder properties, i.e., lack of a stickyor waxy consistency in the solid State. Toxicity of a given substance canbe tested by standard means, such as an MTT assay, as for example describedin Int. J.Pharm. £5_ (1990), p. 249-259. 14

The hygroscopic growth inhibitor is présent in the particles in an amountsuffîcient to minimize or prevent hygroscopic growth of the particles, such that theparticles maintain a size below 3 microns upon aerosolized delivery to the alveoli.

The optimal ratio of active agent to HGI can be ascertained for any given HGI bytesting various proportions in an in vitro model such as described herein. For example,an active agent is typically combined with an HGI, such as hydroxyethylstarch, in the_following w/w proportions: 10/90,25/75,50/50, 75/25, and 90/10, to déterminewhich ratios give a significant réduction in the extent or rate of water uptake in thepowders. From these data, an optimal concentration of HGI can be determined.Different HGIs, in combination with different active agents, and optionally additionalexcipients, will hâve different optimal concentrations, so that each HGI must beseparately tested.

Generally, the particles contain at least about 5 to about 20 percent by weightHGI, preferably at least about 20 to 40 percent HGI, and even more preferably at leastabout 40 to about 60 weight percent or more HGI. The amount of HGI necessary toreduce the moisture absorbing properties of the powder will be less in situationswhere the active agent is a protein or polypeptide, since proteins and polypeptides alsoact to inhibit hygroscopic growth. In instances where the active agent is not a proteinor polypeptide, the particles will preferably contain at least about 40% HGI, with theamount of HGI in the particles ranging front about 40% to 99% by weight. Thepresence of the HGI in the particles maximizes déposition of the aerosolized particlesin the lower respiratory tract, in particular üpon the alveolar surface, as opposed to themouth, throat, and upper airways, thereby increasing the bioavailability of an activeagent delivered to the lung. C. Other Excipients

In addition to the hygroscopic growth inhibitor, the active agent powders ofthe présent invention may optionally be combined with pharmaceutical carriers orexcipients which are suitable for respiratory and pulmonary administration. Suchcarriers may serve simply as bulking agents when it is desired to reduce the activeagent concentration in the powder which is being delivered to a patient. However, the 15 1 i ; s 1

A carriers may also serve to further improve the dispersibility of the powder within apowder dispersion device, functioning to provide more efficient and reproducibledelivery of the active agent and to improve handling characteristics of the activeagent, (e.g., flowability and consistency) to facilitate manufacturing and powderfilling. In particular, the excipient materials can often function to improve thephysical and Chemical stability of the particles, to further minimize the residualmoisture content and hinder moisture uptake, and to enhance particle size, degree ofaggregation, surface properties (i.e., rugosity), ease of inhalation, and targeting of therésultant particles to the deep Iung.

These excipients, if présent, are generally présent in the composition inamounts ranging frora about 1 % to about 50 percent by weight, and include but arenot limited to proteins, peptides, amino acids, and carbohydrates (e.g., sugars,including monosaccharides, di-, tri-, tetra-, and oligosaccharides; derivatized sugarssuch as alditols, aldonic acids, esterified sugars and the like; and polysaccharides orsugar polymers), which may be présent singly or in combination. Exemplary proteinexcipients include sérum albumin such as human sérum albumin (HSA), recombinanthuman albumin (rHA), gelatin, casein, and the like. Représentative aminoacid/polypeptide components, which may also function in a buffering capacity,include alanine, glycine, arginine, betaine, histidine, glutamic acid, aspartic acid,cysteine, lysine, leucine, isoleucine, valine, méthionine, phenylalanine, aspartame, di-and tripeptides such as trileucine, and the like. Carbohydrate excipients suitable foruse in the invention include, for example, monosaccharides such as fructose, maltose, galactose, glucose, D-mannose, sorbose; disaccharides, such as lactose, sucrose, ✓ trehalose, cellobiose, and the like; polysaccharides, such as raffinose, melezitose, andthe like; and alditols, such as mannitol, xylitol, maltitol, lactitol, xylitol sorbitol(glucitol), myoinositol and the like.

The compositions may also include a buffer or a pH adjusting agent.Représentative buffers include organic acid salts such as salts of citric acid, ascorbicacid, gluconic acid, carbonic acid, tartaric acid, succinic acid, acetic acid, or phthalicacid; Tris, tromethamine hydrochloride, or phosphate buffers. Additionally, thecompositions of the invention may include additional excipients/additives, such as 16

Ficolls (a poiymeric sugar), flavoring agents, antimicrobial agents, sweeteners,antioxidants, antistatic agents, surfactants (e.g., polysorbates such as “TWEEN 20”and “TWEEN 80”), and chelating agents (e.g., EDTA). Other pharmaceuticalexcipients and/or additives suitable for use in the matrix compositions describedherein are listed in “Remington: The Science & Practice of Pharmacy”, 19th ed.,Williams & Williams, (1995), and in the “Physician’s Desk Référencé”, 52nd ed.,Medical Economies, Montvale, NJ (1998), the disclosures of which are hereinincorporated by reference. Preferred excipients for use in the présent formulationsinclude mannitol, raffinose, and sodium citrate, leucine, isoleucine, valine, sucrose,raffmose, tri-leucine, and mannitol, ΠΙ. Preparing the Powder Formulation

Dry powder active agent formulations are preferably prepared by spray dryingunder conditions which resuit in a substantially amorphous powder. Spray drying ofthe formulations is carried out, for example, as described generally in the “SprayDrying Handbook”, 5,h ed., K. Masters, John Wiley & Sons, Inc., NY, NY (1991), andin Platz, R., et al., International Patent Publication No. WO 97/41833 (1997), thecontents of which are incorporated herein by reference.

Solutions, émulsions, or suspensions containing the active agent, hygroscopicgrowth inhibitor, and optionally other excipients, are prepared. Solutions orsuspensions for spray drying will typically contain ffom about 0.1 to 10 weightpercent per volume solids. The pH range oT the solutions is generally maintainedbetween about 3 and 9, and will dépend upon the impact of pH on the stability of theactive agent. Near neutral pHs are preferred, since such pHs may aid in maintainingthe physiological compatibility of the powder after dissolution of powder within thelung. The pre-spray-dried formulation may optionally contain additional water-miscible solvents, such as alcohols or acetone. Représentative alcohols are loweralcohols such as methanol, éthanol, propanol, isopropanol, and the like. Therésultant solutions will generally contain active agent at a concentration fforn 0.01%(weight/volume) to about 2% (weight/volume), usually ffom 0.1% to 1%(weight/volume). 17

< 1

The solutions are then spray dried in a conventional spray drier, such as thoseavailable from commercial suppliers such as Niro A/S (Denmark), Buchi(Switzerland) and the like, resulting in a stable, dry powder. Optimal conditions forspray drying the formulations will vary depending upon the formulation components,and are generally determined experimentally. The gas used to spray dry the materialis typically air, although inert gases such as nitrogen or argon are also suitable.Moreover, the température of both the inlet and outlet of the gas used to dry thesprayed material is such that it does not cause deactivation/decompositions of theactive agent in the spray dried material. Such températures are typically determinedexperimentally, although generally, the inlet température will range from about 50° Cto about 200° C while the outlet température will range from about 30° C to about150° C.

Altematively, the dry powders may be prepared by lyophilization, vacuumdrying, spray fireeze drying, super critical fluid processing, or other forms ofevaporative drying. In some instances, it may be désirable to provide the dry powderformulation in a form that possesses improved handling/processing characteristics,e.g., reduced static, better flowability, low caking, and the like, by preparingcompositions composed of fine particle aggregates, that is, aggregates or agglomérâtesof the above-described matrix dry powder particles, where the aggregates are readilybroken back down to the fine powder components for pulmonary delivery, asdescribed, e.g., Johnson, K., et al., U.S. Patent No. 5,654,007, 1997, incorporatedherein by reference. Altematively, the powders may be prepared by agglomeratingthe powder components, sieving the materials to obtain the agglomérâtes,spheronizing to provide a more spherical agglomerate, and sizing to obtain auniformly-sized product, as described, e.g., in Ahlneck, C.; et al., International PCTPublication No. WO 95/09616,1995, incorporated herein by reference. Dry powdersmay also be prepared by blending, grinding, sieving or jet milling formulationcomponents in dry powder form. The resulting powder is generally substantiallyamorphous in form.

Dry powders are preferably maintained under dry {i.e., relatively low humidity) conditions during manufacture, processing, and storage. 18

IV. Characteristics of the Powder

The powder particles of the invention hâve the capability of maintaining anaerodynamic diameter of less than 3 μ when delivered to the alveoli. As can be seenfrom Example 1, powders lacking a hygroscopic growth inhibitor and having an initialMMAD of 3.5 microns behaved like powders having an MMAD from 5-6 microns. _Calculations further indicated that, at equilibrium in the lung, the powder would growto 9 microns MMAD. From this data, it was discovered that the incorporation of ahygroscopic growth inhibitor into the powder formulations described herein waseffective to notably decrease the rate and/or extent of hygroscopic growth of drypowder particles, thereby increasing not only the bioavailability of an active agentcontained in the powder particles, but increasing the dispersibility of suchformulations as well.

For the powders of the invention, the MMAD of the particles in most caseswill be less than about 3 μ prior to pulmonary administration. Typically, the particleswill grow to some degree upon pulmonary administration, although to a degree lessthan they would in the absence of the hygroscopic growth inhibitor, and will typicallyexhibit hygroscopic growth ratios of less than about 2.5, preferably less than about2.0, even more preferably from aSout 1.5 to 2.0, and most preferably less than 1.5.Hygroscopic growth ratios can be determined experimentally, by comparing theMMAD of the powder determined under ambient conditions versus under the MMADdetermined under simulated lung conditions in an environmental chamber(MMADlung/MMADlmbjent). Altematively, the MMAD of a particle under lungconditions can be calculated as follows. First, using the molecular weights of ail ofthe constituents of the particles, the isotonicity for each of the components isdetermined. These isotonicities are then added, to détermine the isotonicity of theparticle. From this value, the volume of solution required to reach isotonicity iscalculated; this volume is then taken to be a volume of a sphere. From this spherevolume, the diameter of the sphere is then calculated, and represents the calculatedMMAD of the particles under conditions found in the lung. This calculated MMADcan then be used to determined the hygroscopic growth ratio as described above. 19 1 '7 Pi I i / w «

The moisture uptake characteristics of the particles are typically determined bymoisture sorption experiments. Moisture sorption data for powders can be determinedby a number of techniques, such as moisture sorption balance or thermal activitymonitor (TAM). Moisture sorption balances are determined by measuring the weightloss or gain as a function of increasing or decreasing relative humidities at a constanttempérature. A carrier gas introduced at a known RH is created by mixing a wet and _dry stream of gas. This gas is then exposed to the sample located in a non-hygroscopic sample cup attached to a microbalance. Depending on the morphologyof the sample, it may absorb, adsorb or desorb moisture. This sorption is detected bythe microbalance as a weight increase or decrease. A computer program is used tocollect data point (generally time, température, relative humidity and weight) through-out the experiment and at user defmed equilibrium points.

The powders of the invention may also be characterized by a sorption index, SI, i.e., the sum of the percent weight gain of the powder determined at 10%, 20%, 30% and 40% relative humidity, divided by four. The sorption index is determinedusing a gravimétrie sorption analyzer, such as the DVS-1000, manufactured bySurface Measurements Systems (London, U.K.), or by moisture balance, using aninstrument such as the MB 300G, manufactured by VTI Corporation (Hialeah, FL).Powders of the invention will typiêally hâve sorption indices less than about 7.5,preferably less than about 7.0, more preferably less than about 6.5, and mostpreferably below 6.0. Powders exhibiting such SI values are shown in Example 2.

Powders preferred in the présent invention are those which take up waterslowly, i.e., at a rate of less than about 0.75% moisture as a function of relativehumidity, preferably less than about 0.50% moisture as a function of relativehumidity, and more preferably less than about 0.35% moisture as a function ofrelative humidity, and most preferably less than about 0.25% moisture as a function ofrelative humidity (e.g., see Fig. 1). As another measure, the particles absorb less thanabout 60% moisture (wt), preferably less than 30% moisture, more preferably lessthan 25% moisture, even more preferably less than 20% moisture, and most preferablybetween about 10 to 20% by weight water under humid conditions, 80% relativehumidity. Figs. 1 and 2 illustrate how powders containing a hygroscopic growth 20

inhibiting agent, when compared to powder formulations lacking an HGI, exhibit botha decreased rate of water uptake (indicated by smaller slopes in comparison to thecontrol formulation) and a lower overall extent of moisture uptake.

In looking at Fig. 1, under conditions of 80% relative humidity, the spray-dried control powder containing 20% insulin, 59% sodium citrate, 18% mannitol and2.6% glycine absorbed 60% moisture by weight, while under the same conditions,spray-dried dextran, hydroxypropylmethylcellulose, hydroxypropyl-P-cyclodextrin,and hydroxyethylstarch, absorbed 24%, 16%, 16%, and 24% moisture, respectively,thus illustrating the superior hygroscopic growth inhibiting properties of thesematerials. Similarly, in looking at Fig. 2, under conditions of 80% relative humidity,while the control absorbed 60% moisture, under the same conditions, spray driedpowders containing 20% insulin, 40% hydroxyethylstarch, 2.6% glycine, 18%mannitol, 19% sodium citrate, and 100% hydroxyethylstarch, absorbed 50% and 24%moisture, respectively. Moreover, in both figures, the rate of water uptake wassubstantially reduced for the HGI materials, when compared to the Controls.

The powders of the invention can also be characterized by maintaining gooddispersibilities when exposed to the hot and humid conditions such as those found inthe environment of the lung. The powders of the invention will generally exhibit adrop in emitted dose (ED) at 32°C and 95% relative humidity (when compared to theED under ambient conditions) of no more than about 30% (meaning EDambien, minusEDhumid equals 30 or less), preferably no more than about ffom about 20 to 25%, morepreferably no more than 15%, and most preferably no more than about 10%.

As an illustration, Example 2 shows powder formulations whose EDs, whenevaluated in an environmental chamber, decrease only ffom about 10-15% (60%maltodextrin formulations). Also exhibiting good EDs under lung conditions werepowder formulations containing 60% hydroxyethylstarch. As can be seen ffom thedata in Table 1, increasing the amount of hydroxyethylstarch ffom 40% to 60%(samples 2/3 versus 4/5) was effective to reduce the environmental chamber ED drop.On average, these formulations showed a drop of about 20% in ED under lungconditions, while maintaining ED values of about 55%. 21

The emitted dose (ED) of the HGI-containing powders, under ambientconditions, is greater than 30% and usually greater than 40%. More preferably, theemitted dose of the powders of the invention is greater than 50%, and is often greaterthan 60%. The powders of the invention typically contain a large proportion of small 5 aérosol particle sizes and are thus extremely effective when delivered in aerosolizedform, in (i) reaching the alveolar région of the lung, (ii) diffusion to the interstitium,and (iii) subséquent passage into the bloodstream through the endothélium.

The dry powders of the invention will generally hâve an overall moisturecontent under ambient conditions below about 10% by weight, usually below about 10 5% by weight, and preferably below about 3% by weight. Such low moisture- containing solids tend to exhibit a greater stability than the corresponding “highmoisture” solids. V. Pulmonarv Administration of the Powder 15 The HGI-containing dry powder formulations described herein are preferably delivered using any suitable dry powder inhaler (DPI), i.e., an inhaler device thatutilizes the patient's inhaled breath as a vehicle to transport the dry powder drug to thelungs. Preferred are Inhale Therapeutic Systems’ dry powder inhalation devices asdescribed in Patton, J.S., et al., U.S7 Patent No. 5,458,135 (1995); Smith, A., et al., 20 U.S. Patent No. 5,740,794, ( 1998); and Smith, A., et al., U.S. Patent No., 5,785,049,(1998).

When administered using a device of this type, the dry powder is contained ina réceptacle having a puncturable lid or other access surface, preferably a blisterpackage or cartridge, where the réceptacle may contain a single dosage unit or 25 multiple dosage units. Convenient methods for fîlling large numbers of cavities withmetered doses of dry powder médicament are described, e.g., in Parks, D.J., et al.,International Patent Publication WO 97/41031, (1997).

Also suitable for delivering the dry powders described herein are dry powder inhalers of the type described, for example, in Cocozza, S., U.S. Patent No. 3,906,950, 30 (1974), and Cocozza, S., U.S. Patent No. 4,013,075, (1977), wherein a premeasured dose of dry powder for delivery to a subject is contained within a hard gelatin capsule. 22

1JB .·«»·*- * A l/οι • 4b

Other dry powder dispersion devices for pulmonarily administering drypowders include îhose described, for example, in Newell, R.E., et al., European PatentNo. EP 129985, (1988); in Hodson, P.D., et al.. European Patent No. EP 472598,(1996); in Cocozza, S., et al., European Patent No. EP 467172, (1994), and in Lloyd, L.J. et al., U.S. Patent No. 5,522,385, (1996). Also suitable for delivering the matrixdry powders of the invention are inhalation devices such as the Astra-Draco“TURBUHALER”. This type of device is described in detail in Virtanen, R., U.S.Patent No. 4,668,218, (1987); in Wetterlin, K., et al, U.S. Patent No. 4,667,668,issued May 26, (1987); and in Wetterlin, K., et al., U.S. Patent No. 4,805,811, (1989).Also suitable are devices which employ the use of a piston to provide air for eitherentraining powdered médicament, lifting médicament from a carrier screen by passingair through the screen, or mixing air with powder médicament in a mixing chamberwith subséquent introduction of the powder to the patient through the mouthpiece ofthe device, such as described in Mulhauser, P., étal, U.S. Patent No. 5,388,572, (1997).

The HGI-containing dry powders may also be delivered using a pressurized,metered dose inhaler (MDI) containing a solution or suspension of drug in apharmaceutically inert liquid propellant, e.g., a chlorofluorocarbon or fluorocarbon, asdescribed in Laube, et al., U.S. Patent No. 5,320,094, (1994), and in Rubsamen, R.M.,et al, U.S. Patent No. 5,672,581 (1994).

Prior to use, the HGI-containing dry powders are generally stored underambient conditions, and preferably are storêd at températures at or below about 25°C,and relative humidities (RH) ranging from about 30 to 60%. More preferred relativehumidity conditions, e.g., less than about 30%, may be achieved by the incorporationof a desiccating agent in the secondary packaging of the dosage form. The respirabledry powders of the invention are characterized not only by good aérosol performance,but by good stability, as well.

When aerosolized for direct delivery to the lung, an active agent contained inthe dry powder formulations described herein will exhibit an increased in-lungbioavailability, due to the presence of the HGI within the powder particles, whichallows a greater percentage of the inhaled particles to reach the deep lung without 23

prior déposition in the upper airways due to hygroscopic growth. Such HGI-containing formulations thus allow for the administration of smaller quantities of drugper unit dose, and may even eliminate the need for multiple inhalations per day.Moreover, the presence of the HGI provides enhanced stability to the powderformulation by reducing or preventing moisture uptake, thereby enhancing the shelfIife and shipping stability of the dry powder formulations.

The disclosure of each publication, patent or patent application mentioned inthis spécification is incorporated by reference herein to the same extent as if eachindividual publication, patent or patent application were specifically and individuallyindicated to be incorporated by reference.

The following examples illustrate, but in no way are intended to limit thescope of the présent invention.

Examples

Materials and Methods

Salmon calcitonin (sCalcitonin) was purchased from Bachem (Torrance, CA).

Human Sérum Albumin (HSA) was purchased from Miles Inc. (Kankakee, IL).Sodium citrate dihydrate was obtained from J.T. Baker (Phillipsburg, NJ). L,a-dipalmitoylphosphatidylcholine (DPPC) is obtained from Avanti Polar Lipids,Alabama.

Example 1

The following active agent containing particles were prepared to investigatemoisture uptake and hygroscopic growth properties. 24 11,3 Ί A. Powder Production

Salmon Calcitonin powders were prepared as follows. Bulk sCalcitonin wasdissolved in sodium citrate buffer containing mannitol and HSA to give an aqueoussolution having a final solids concentration of 7.5 mg/ml and a pH of 6.7±0.3. Thesolution was then filtered through a 0.22 pm filter, followed by spray drying using aBuchi 190 mini spray dryer (Buchi Labortechnik AG, Meierseggstrasse, Switzerland).The spray dryer was operated at an inlet température between 110°C and 120°C, aliquid feed rate of 5 ml/min, and an outlet température between 70°C and 80°C,resulting in the collection of a fine white amorphous powder,

Powders containing the following hygroscopic growth inhibitors (HGIs):DPPC, cyclodextrin, hydroxyethylstarch, dextran, dextranomer, maltodextran,hydroxypropylcellulose, hydroxypropylmethylcellulose, and cellulose ethylhydroxyethyl ether are similarly prepared.

The composition of the powder absent the HGI was 5% sCalcitonin/6.25%HSA/ 73.75% mannitol/15% citrate by weight. The powder incorporating the HGIpossesses the same relative amounts of sCalcitonin/HSA/mannitol/citrate, but alsocontains front about 10% to 90% by weight of the hygroscopic growth inhibitor.

The resulting powders are stored in tightly capped containers in a dryenvironment (<10% RH) prior to hygroscopic growth analysis. B. Powder Analysis

The particle size distribution of the'sCalcitonin powder was measured byliquid centrifugal sédimentation in a Horiba CAPA-700 Particle Size Analyzerfollowing dispersion of the powders in Sedisperse A-l 1 (Micrometrics, Norcross,GA).

The moisture content of the sCalcitonin powder was measured by the KarlFischer technique using a Mitsubishi CA-06 Moisture Meter.

The aérosol particle size distribution was determined using a cascade impactor(Graseby Andersen, Smymâ, GA) at a flow rate of 28 1/min, ignoring powder loss oninlet manifold and stage 0 j et plate. 25

1

Emitted doses (ED) were evaluated using an Inhale Therapeutic Systems’aérosol device, similar to that described in W096/09085. The emitted dose is definedas the percentage of the nominal dose contained within a blister package that exits themouthpiece of the aérosol device and is captured on a glass fiber filter (Gelman, 47 5 mm diameter) through which a vacuum was drawn (30L/min) for 2.5 secondsfollowing device actuation. ED is calculated by dividing the mass of the powdercollected on the filter by the mass of the powder in the blister pack.

The ED of 5% sCalcitonin powders ranged between 52.6 and 53.9%.

The MMAD of the 5%s Calcitonin powders was approximately 3.5-3.6 10 microns.

These analyses are similarly perfoimed on the DPPC-containing sCalcitoninpowders. C. Particle Growth 15 The following study was undertaken to explore the bioavailability of sCalcitonin formulations delivered to the lung as a dry powder aérosol.

Non-H Gl-sCalcitonin particles were administered to 16 healthy volunteers.Each subject received a dry powder aérosol dose. The aerosolized dose containedapproximately 2.5mg of powder, coïitaining approximately 750IU (125pg) of salmon 20 calcitonin, radiolabelled with 10 MBq 99mTc pertechnitate. The particles were aerosolized using the Inhale Therapeutic Systems’ aérosol devices, described above.

The dose of sCalcitonin delivered trithe lung and the lung periphery (deeplung) was determined using a modification of standard gamma caméra techniques.Quantitation of the sCalcitonin reaching the systemic circulation was achieved by 25 radioimmunoassay of sérum samples taken over 6 hours post dose (“Ultra-SensitiveRadioimmunoassay kit for the Quantitative Radioimmunoassay for the QuantitativeDétermination of salmon calcitonin in sérum and Plasma”, Diagnostic SystemsLaboratories Inc.)

Bioavailability was determined by comparing the dose corrected AUC (area 30 under the curve) estimâtes using the peripheral (alveolar) dose. Simple trapézoïdalintégration was used to détermine AUCs. Relative bioavailability was determined 26 relative to subcutaneous injection. Statistical analysis of both the gamma caméradéposition data and the relative bioavailability data were performed using a Wilcoxonmatched-pairs signed ranks test. The Wilcoxon test is a non-parametric testappropriate for small sample size. A p value of < 0.05 was considered to besignificant.

The size distribution of the powder without HGI before and after theradiolabeling process was essentially unchanged. In examining the régionaldéposition patterns after inhalation, 21.6% of the inhaled dose of powder reached theperipheral Jung (45.6% reached the whole lung including the peripheral lung), whilethe loss to the mouth and oropharynx was 54.4%.

The bioavailability of the salmon calcitonin powder, relative to subcutaneousinjection, was 28.0% for the dose delivered to the peripheral lung. Despite the valueof 3.5 MMAD obtained for the aérosol size distribution, this powder acted like apowder having an MMAD of between 5 and 6 microns. This can be accounted for asa resuit of the hygroscopic growth of the particles as they pass through the airways,due to the hygroscopic nature of the formulation.

Support for this mechanism was provided by calculating the aerodynamicequilibrium growth ratio for the formulation, which was 2.53. This ratio indicatedthat, under airway conditions, the particles grow, and at equilibrium, fforn a startingMMAD of 3.5 microns, the aérosol particles grow to 9 microns MMAD (i.e, theparticles grow to 2.53 times their original aerodynamic diameter). Equilibriumgrowth ratios are determined by calculating the solids concentration (powder to waterratio) at which an aqueous solution of the powder becomes isotonie, that is, theconcentration at which a liquid droplet reaches equilibrium in the lung, which thenallows calculation of the MMAD of the isotonie droplet. The growth ratio is: MMADisotonjc drOp|ct/MMAD pow(jer particlesambienc

Accordingly, sCaîcitonin powders which maintain an MMAD of 3.0 micronswhen delivered to the alveoli are prepared by incorporating one or more HGIs into theparticles in concentrations of between about 10-90%, particularly 10,20, 30, 40, 50,60, 70, 80 and 90% by weight HGI. The résultant powders are then tested asdescribed above to détermine their hygroscopic growth, if any, when exposed to the 27 environmental conditions of the lung. Powders according to the invention are thosewhich exhibit an inhibition or réduction of hygroscopic growth, and more specifically,maintain that the particle size distribution remains below 3.0 microns MMAD whendelivered to the peripheraî lung, to thereby increase déposition at the peripheral lung 5 and increase the in-lung bioavailability of an active agent delivered pulmonarily.

Example 2

Powder Measurements in an Environmental ChamberSpray-dried powders containing one or more hygroscopic growth inhibitors 10 were prepared as described in Example 1. The relative weight percentages of thepowder components are provided in Table 1 below.

To assess the hygroscopic behavior of aérosol powders, dry inhalable powderswere placed in an environmental chamber (Enviro-Chamber) which simulâtes thephysiological conditions of the human lung (32°C and 95%RH). The chamber was 15 monitored by pre-calibrated humidity and température probes (Digi-sense). Pre-collected data by this pre-calibrated probe showed both 95% RH and 32°C wereproduced consistently by the Enviro-Chamber for a long period of time.

Emitted dose and particle size were measured under standard (24°C and 40%)and humidifîed (32°C and >95%RH) conditions. Sampling under standard conditions 20 was conducted inside the environmental chamber with the System tumed off.

The data collected under standard conditions was used as the control baseline.Membrane filters (47-mm) were used for the ED collections and an Andersen cascadeimpactor for the particle size distribution measurements. 28

Claims (23)

1. It is claimed:

   1. Particles for delivery of an active agent to the alveoli of a human patient, 5 said particles comprising the active agent and a hygroscopic growth inhibitor, whereinthe hygroscopic growth inhibitor is incorporated within the particles, and wherein the .particles exhibit a drop in emitted dose under simulated lung conditions of no morethan about 25%.
2. 2. The particles of daim 1, wherein the hygroscopic growth inhibitor is 10 selected from the group consisting of double chain phospholipids, cyclodextrins, hydroxyethylstarch, dextran, dextranomer, maltodextrins, hydroxypropylcellulose,hydroxypropyimethylcellulose and cellulose ethyl hydroxyethyl ether.
3. 3. The particles of claim 1 or claim 2, where the hygroscopic growth inhibitor 15 is selected from the group consisting of β-cyclodextrin, hydroxypropyl-β- cyclodextrin, sulfobutylether β-cyclodextrin, dextran, hydroxypropyimethylcellulose,hydroxyethylstarch, and maltodextrin.
4. 4. The particles of any of cîâims 1 to 3, wherein the hygroscopic growthinhibitor is présent in the powder at an amount sufficient for the powder to exhibit a 20 rate of moisture uptake of no greater than about 0.50% as a function of relativehumidity.
5. 5. The particles of any of daims 1 to 4, wherein the hygroscopic growthinhibitor is présent in the powder in an amount sufficient for the powder to exhibit anoverall extent of water uptake of no greater than about 30 weight percent at a relative 25 humidity of 80%.
6. 6. The particles of any of daims 1 to 5, having an emitted dose under ambientconditions of at least 60%.
7. 7. The particles of any of daims 1 to 6, containing from about 20 percent toabout 99 percent by weight hygroscopic growth inhibiting agent. 33
8. 8. The particles of any of daims 1 to 7, which when delivered pulmonarily,are deposited in the deep lung to an extent greater than 20% of the nominal dose.
9. 9. The particles of any of daims 1 to 8, wherein said hygroscopic growthinhibitor is effective to increase the bioavailabiîity of said active agent when deliveredto the lung by at least 5 percent, when compared to the bioavailabiîity observed for theactive agent contained in the same particles absent said hygroscopic growth inhibitorand delivered to the lung.
10. 10. Particles for delivery of an active agent to the alveoli of a human patient,said particles comprising the active agent and a hygroscopic growth inhibitorincorporated within the particles, wherein the particles hâve a sorption index of lessthan about 6.5.
11. 11. The particles of daim 10, wherein the hygroscopic growth inhibitor isselected front the group consisting of double chain phospholipids, cyclodextrins,hydroxyethylstarch, dextran, dextranomer, maltodextrins, hydroxypropylcellulose,hydroxypropylmethylcellulose, cellulose ethyl hydroxyethyl ether.
12. 12. The particles of daim 10 or daim 11, wherein the hygroscopic growthinhibitor is selected from the group consisting of β-cyclodextrin, hydroxypropyl-β-cyclodextrin, -β-cydodextrin sulfobutyl ether, dextran, hydroxypropylmethylcellulose, hydroxyethylstarch, and maltodextrin.
13. 13. The particles of any of daims 10 to 12, having an emitted dose underambient conditions of at least 60%.
14. 14. The particles of any of daims 10 to 13, containing from about 20 percentto about 99 percent by weight hygroscopic growth inhibiting agent.
15. 15. Particles for delivery of an active agent to the alveoli of a human patient,said particles comprising the active agent and a hygroscopic growth inhibitor 34 1 1 7 H 1 incorporated within the particles. wherein the particles maintain an aérosol particle*size distribution below 3 microns MMAD when delivered to the alveoli.
16. 16. A method for preparing particles for delivery of an active agent to thealveoli of a human patient, comprising; preparing a mixture of a hygroscopic growth inhibitor, an active agent, and a _solvent; and · spray drying the mixture to obtain homogenous particles of the hygroscopicagent and the active agent; wherein the particles exhibit a drop in emitted dose under simulated lungconditions of no more than about 25%.
17. 17. The method of cîaim 16, wherein the hygroscopic agent is selected fromthe group consisting of double chain phospholipids, cyclodextrins,hydroxyethylstarch, dextran, dextranomer, maltodextrins, hydroxypropylcellulose,hydroxypropylmethylcellulose and cellulose ethyl hydroxyethyl ether.
18. 18. The method of claim 17, wherein the hygroscopic agent is selected fromthe group consisting of β-cyclodextrin, hydroxypropyl-P-cyclodextrin, β-cyclodextrinsulfonylbutyl ether, dextran, hydroxypropylmethylcellulose, hydroxyethylstarch, andmaltodextrin.
19. 19. The method of any of daims 16 to 18, where the solvent is vvater.
20. 20. The method of any of cîaims 16 to 19, wherein the homogeneous particlescontain from about 20 percent to about 99 percent by weight hygroscopic growthinhibiting agent.
21. 21. Aerosolized active particles of any of daims 1 to 15, for use in amethod for delivery of an active agent to the lungs of a human patient, said methodcomprising administering said particles by inhalation. 35 117 8 1
22. 22. The particles of daim 21, wherein said active agent is administered bymeans of a dry powder inhaler.
23. 23. A composition containing an active agent-containing dry powderparticles for inhalation and a hygroscopic growth inhibiting agent for use in amethod for increasing the quantity of an inhaled active agent deposited in the deeplung, wherein, upon aerosolization and inhalation of the particles, at least 20% ofthe nominal dose is deposited in the deep lung. 36