WO2003020283A2

WO2003020283A2 - Method for treating diabetic retinopathy

Info

Publication number: WO2003020283A2
Application number: PCT/EP2002/009612
Authority: WO
Inventors: Kenneth E. Green; Frances Elizabeth Kane
Original assignee: Novartis Pharma GmbH Austria; Novartis Erfindungen Verwaltungs GmbH; Novartis AG
Current assignee: Novartis Pharma GmbH Austria; Novartis AG
Priority date: 2001-08-29
Filing date: 2002-08-28
Publication date: 2003-03-13
Anticipated expiration: 2004-02-29
Also published as: WO2003020283A3

Abstract

The present invention is directed to a method for protecting the vision of a human suffering from diabetes comprising administering to a human suffering from diabetes an amount of a composition comprising a docosanoid active agent effective to increase retinal.

Description

Method For Treating Diabetic Retinopathy

Diabetic retinopathy is a highly specific vascular complication of both type 1 and type 2 diabetes, which is strongly related to the duration of diabetes. Overall, diabetic retinopathy is estimated to be the most frequent cause of new cases of blindness among adults aged 20-74 years.

In general, diabetic retinopathy first presents as nonproliferative diabetic retinopathy. This phase is characterized by increased vascular permeability in the retina, where the arteries become weakened and leak, forming small, dot-like hemorrhages. These leaking vessels often lead to swelling or edema in the retina and decreased vision, particularly if the swelling affects the macula, which is the portion of the retina that renders fine details. Often the blood vessels become so damaged that they close. This typically leads to the next stage, which is known as proliferative diabetic retinopathy. In this stage, circulation problems (i.e., closed or very leaky vessels) cause areas of the retina to become oxygen-deprived or ischemic. New, fragile, vessels develop as the circulatory system attempts to maintain adequate oxygen levels within the retina. This process is called retinal neovascularization. Unfortunately, these delicate vessels hemorrhage easily. Blood may leak into the retina and vitreous, causing spots or floaters, along with decreased vision. In the later phases of the disease, continued abnormal vessel growth and scar tissue may cause serious problems such as retinal detachment and glaucoma.

It has now been discovered that it is possible to increase the retinal blood flow of individuals with diabetes by the administration of docosanoid active agents. Thus, in one aspect, the present invention is directed to a method for protecting the vision of a human suffering from diabetes comprising administering to a human suffering from diabetes an amount of a composition comprising a docosanoid active agent effective to decrease the mean circulation time for bloodflow in the retina of the human.

In another aspect, the present invention is directed to a method for inhibiting retinal neovascularization in a human suffering from diabetes comprising administering to a human suffering from diabetes an amount of a composition comprising a docosanoid active agent effective to inhibit the formation of new blood vessels in the retina of the human.

In another aspect, the present invention is directed to a method of inhibiting at least one of increased retinal capillary basement membrane thickening and retinal capillary cell density, wherein said increased retinal capillary basement membrane thickening and retinal capillary cell density are indicative of early proliferative retinopathy in a human suffering from diabetes, comprising administering to a human suffering from diabetes an amount of a composition comprising a docosanoid active agent effective to inhibit at least one of increased retinal capillary basement membrane thickening and retinal capillary cell density indicative of early proliferative retinopathy.

All patents, patent applications, and publications cited herein are incorporated by reference in their entirety. In the event of a conflict between the present specification and citations incorporated by reference, the present specification is controlling.

The active agents useful in the practice of the invention may be selected from the group consisting of docosanoids, metabolites thereof, chemical derivatives thereof, structural analogs thereof, salts thereof, docosanoid prodrugs, and mixtures thereof, referred to herein as "docosanoid active agent" or merely "active agent". A docosanoid active agent is "active" in the sense that the agent causes an increase in retinal blood flow when applied to the ocular environment of a patient in need of reduction of intraocular pressure.

A docosanoid, as used herein, refers to a group of compounds related to docosahexaneoic acid. Docosanoids are found in human and animal tissues and organs and may be synthetically produced. The preferred docosanoids are those which are useful in therapeutic ophthalmic applications, especially those which have also been shown to reduce intraocular pressure.

A group of docosanoids, which have been found to be useful in decreasing intraocular pressure, are disclosed in U.S. Patent Nos. 4,599,353; 5,296,504; 5,422,368; and 5,578,618. These patents are incorporated herein by reference for the disclosure of docosanoid active agents, which are useful for treating diabetic retinopathy.

U.S. Patent Nos. 5,106,869; 5,221,763 5,208,256; 5,001,153; 5,151,444; 5,166,178; and 5,212,200 are also all incorporated herein by reference for the disclosure of docosanoid active agents which are useful for treating diabetic retinopathy.

Docosanoids useful in the methods of the present invention may be docosanoid salts, or those docosanoids with an esterified carboxyl group. Suitable docosanoid salts are ophthalmically acceptable salts, including without limitation thereto, salts of alkali metals such as sodium or potassium; salts of an alkaline earth metal such as calcium or magnesium; salts of ammonia, methylamine, dimethylamine, cyclopentylamine, benzylamine, piperidine, monoethanolamine, diethanolamine, monomethylmonoethanolamine, tromethamine, lysine and tetralkylammonia; and the like and mixtures thereof. Suitable docosanoid esters are ophthalmically acceptable esters, including without limitation thereto, methyl, ethyl, propyl, butyl, isopropyl, t-butyl, 2-ethylhexyl, straight or branched-chain alkyl esters which may contain an unsaturated bond. Suitable esters include an ester having an alicyclic group such as a cyclopropyl, cyclopentyl, olr cyclohexyl group; an ester containing an aromatic group such as a benzyl or phenyl group (wherein the aromatic group may contain one or more substituents); a hydroxyalkyl or alkoxyalkyl ester such as hydroxyethyl, hydroxyisopropyl, polyhydroxyisopropyl, methoxyethyl, ethaoxyethyl or methoxyisopropyl groups; an alkysilyl ester (e.g., a trimethylsilyl or triethylsilyl ester); and a tetrahydropyranyl ester.

Another group of docosanoids useful in the present invention are those disclosed in U.S. Patent No. 5,208,256, which is incorporated herein by reference for its disclosure of docosanoid compounds. Isopropyl unoprostone (Ul) is exemplary of the docosanoids useful in the present invention. The structure of isopropyl unoprostone is given below and a method of preparation is outlined in U.S. Patent 5,212,200, which is incorporated by reference.

Useful docosanoid concentrations are those amounts, which will ameliorate and/or prevent further progression of diabetic retinopathy. Useful concentrations depend on a number of factors, including the efficacy of the docosanoid in the presence of the other components, the volume of medicament applied, and the frequency and duration of application.

One useful concentration of active agents is the range between about 0.001 and about 0.30 weight percent. Other useful concentration ranges are between about 0.06 and about 0.24 weight percent active agent, and concentrations between about 0.10 and about 0.20 weight percent. Concentrations of about 0.12 weight percent and about 0.15 weight percent are also contemplated. The most useful concentration in any specific application depends on a number of factors, such as the concentrations and chemical nature of other ingredients as well as the delivery method and conditions.

"Diabetes," as used herein, refers to any form of diabetes where decreased retinal blood flow or retinopathy is an associated complication, and specifically includes type 1 diabetes (i.e., juvenile onset diabetes) and type 2 diabetes. "Retinal bloodflow," as used herein, refers to volume of blood per unit of time that flows through the four major retinal artery/vein pairs exiting from the optic disc and perfusing the four retinal quadrants.

"Inhibit," as used herein with respect to growth of new blood vessels in the retina, means a decrease in the rate or amount of new blood vessel growth in the retina relative to the rate or amount of growth that would occur absent administration of a docosanoid active agent as disclosed herein.

A surfactant, as used herein, refers to a surface-active agent, which improves the solubility of a substance, e.g., an active or drug, in a solvent. A non-ionic surfactant, as used herein, refers to a surfactant, which possesses no easily ionizable groups.

U.S. Patent No. 5,208,256 discloses the use of Polysorbate 80 as a surfactant for docosanoid-containing ophthalmic compositions. Polysorbate 80 improves the solubility of isopropyl unoprostone, so that a higher concentration of isopropyl unoprostone can be used in an aqueous solution form.

However, it has been discovered that while increasing the concentration of Polysorbate allows higher docosanoid concentrations in aqueous solutions, the effectiveness of preservatives decreases with increasing Polysorbate 80 concentrations.

One embodiment of the present invention employs a combination of two or more non- ionic surfactants (e.g.., a first and a second non-ionic surfactant). Certain combinations of non-ionic surfactants have been found to increase docosanoid active agent solubility without reducing preservative effectiveness as much as Polysorbate 80 alone in the same concentration.

Useful non-ionic surfactants are those which, in combination, exhibit better ophthalmic tolerance than Polysorbate 80 alone and/or which do not reduce preservative effectiveness or reduce preservative effectiveness less than Polysorbate 80 alone in the same concentration.

The two or more non-ionic surfactants may be selected from the group of non-ionic surfactants including, without limitation, polyoxyethylene sorbitan fatty acid esters such as Polysorbates 20, 60 and 80; polyoxyethylene alkyl ethers such as Brij's (e.g., BRIJ 97 or BRIJ 98 from ICI Surfactants, Wilmington, DE), Cremophors (such as Cremophor RH or Cremophor EL), Volpo (e.g., VOLPO 10 and VOLPO 20 from Croda, Inc., Parsippany, NJ) and equivalents thereof. A particularly useful group includes polyoxyethylene sorbitan monooleates (e.g., Polysorbate 80), polyoxyethylene 10 oleyl ethers (e.g., Brij 97) and polyoxyethylene 20 oleyl ethers (e.g., Brij 98). A particularly useful combination of surfactants is the combination of a polyoxyethylene sorbitan fatty acid ester (especially Polysorbate 80) with a polyoxyethylene alkyl ethers (e.g., BRIJ 97 or BRIJ 98). Specific, useful combinations are the combination of Polysorbate 80 with BRIJ 97 or Polysorbate 80 with BRIJ 98.

It has been found that use of at least two surfactants together provides an unexpected synergistic result in that the total concentration of surfactant required to achieve a desired docosanoid active agent solubility is less that the concentration required for an individual surfactant. In addition, certain combinations of surfactants actually improve the preservative effectiveness. Specifically, the combination of Polysorbate 80 with a BRIJ surfactant improves benzalkonium chloride preservative effectiveness relative to the same concentration of Polysorbate 80 alone. Furthermore, this combination of surfactants improves the emulsion stability of the formulation.

The total concentration of surfactant used depends, in large part, on the solubilizing character of the particular surfactant or surfactants and the concentration and chemical nature of the particular docosanoid active agent which the surfactant is intended to solubilize. In general, the total surfactant concentration is between about 0.1 and about 5 weight percent. The surfactant concentration range is also useful between about 0.3 and about 2.0 weight percent. Surfactant concentrations between about 0.5 and about 1.5 weight percent are also useful.

A "preservative", as used herein, refers to an additive which inhibits both microbial growth and kills microorganisms which inadvertently contaminate the ophthalmic solution upon exposure to the surroundings. The preservative may be selected from a variety of well known preservatives, including hydrophobic or non-charged preservatives, anionic preservatives, and cationic preservatives. A "preservative enhancing agent", as used herein, refers to an additive which increases the preservative effectiveness of a preservative, or the preservative effectiveness of a preserved formulation, but which would not typically be used solely to preserve an ophthalmic formulation.

Cationic preservatives include, without limitation, polymyxin B sulfate, quaternary ammonium compounds, poly(quaternary ammonium) compounds, p-hydroxybenzoic acid esters, certain phenols and substituted alcohols, benzalkonium chloride, benzoxonium chloride, cetylpridinium chloride, benzethonium chloride, cetyltrimethyl ammonium bromide, chlorhexidine, poly(hexamethylene biguanide), and mixtures thereof. Poly(quatemary ammonium) compounds include BUSAN 77, ONAMER M, MIRAPOL A15, IONENES A, POLYQUATERNIUM 11, POLYQUATERNIUM 7, BRADOSOL, AND POLYQUAT D-17- 1742. A preferred preservative for the ophthalmic field is benzalkonium chloride.

Anionic preservatives include, without limitation, 1 -octane sulfonic acid (monosodium salt); 9-octadecenoic acid (sulfonated); ciprofloxacin; dodecyl diphenyloxide-disulfonic acid; ammonium, potassium, or sodium salts of dodecyl benzene sulfonic acid; sodium salts of fatty acids or tall oil; naphthalene sulfonic acid; sodium salts of sulfonated oleic acid; organic mercurials such as thimerosal (sodium ethylmercurithiosalicylate); thimerfonate sodium (sodium p-ethylmercurithiophenylsulfonate).

Hydrophobic or non-ionic preservatives include, without limitation, 2,3-dichloro-1 ,4- naphthoquinone; 3-methyl-4-chlorophenol; 8-hydroxyquinoline and derivatives thereof; benzyl alcohol; bis(hydroxyphenyl) alkanes; bisphenols; chlorobutanol; chloroxylenol; dichlorophen[2,2'-methylene-bis(4-chlorophenol)]; ortho-alkyl derivatives of para- bromophenol and para-chlorophenol; oxyquinoline; para-alkyl derivatives of ortho- chlorophenol and ortho-bromophenol; pentachlorophenyl laurate; phenolic derivatives such as 2-phenylphenol, 2-benzyl-4-chlorophenol, 2-cyclopentyl-4-chlorophenol, 4-t-amylphenol, 4-t-butyl phenol, and 4- and 6-chloro-2-pentylphenol; phenoxy fatty acid polyester; phenoxyethanol; and phenylethyl alcohol.

In one embodiment, the preservative is present in the solution in an amount sufficient to kill microbes, which may inadvertently enter the dispensing container over the period of use. The desirable concentration will depend on a number of factors, including the strength of the preservative, the conditions of dispenser use, and the length of time the dispenser and solution will be in service. Generally, the strong preservative may be present in a concentration from about 0.00005 to about 0.2 weight percent, more preferably the concentration is about 0.005 to about 0.2 weight percent, and even more preferably, the strong preservative concentration is about 0.01 to about 0.015 weight percent.

An ophthalmically acceptable agent which enhances the effectiveness of the preservative may be advantageously added to the formulation. Examples of preservative enhancing agents useful in accordance with the present invention include, without limitation thereto, chelating agents such as ethylene diamine tetraacetic acid (EDTA), derivatives thereof, salts thereof and mixtures thereof.

The preservative enhancing agent is intended to overcome any remaining microbial burden, which the strong preservative did not. For example, while benzalkonium chloride kills nearly all Psuedomonas, there may remain some resistant strain or strains, which may propagate over time. Thus, it is desirable to add a preservative enhancing agent, such as EDTA, to kill the remaining benzalkonium chloride-resistant Psuedomonas. It is believed that EDTA destroys the Psuedomonas by chelation with Ca⁺⁺ ions. Accordingly, a preferred class of weak preservatives are chelating agents, especially calcium chelating agents.

The use of EDTA is particularly preferred in part because EDTA prevents the growth of benzalkonium chloride-resistant Psuedomonas. However, EDTA has also been found to have advantages in addition to its preservative enhancing function. EDTA can be used to buffer the formulation to achieve the desired pH. Further, EDTA may provide a stabilization function for the docosanoid active agent, thereby inhibiting degradation and increasing shelf life.

The most effective concentration of preservative enhancing agent will depend on a number of factors, such as the efficacy of the strong preservative at the chosen concentration and the preservative enhancing effectiveness of the preservative enhancing agent. The concentration of preservative enhancer should be high enough to deactivate amounts of Psuedomonas, which are dangerous to the patient, but the concentration should be low enough to avoid any substantial ocular discomfort.

If a chelating agent such as EDTA is used, concentrations between about 0.01 and about 0.1 weight percent are useful. Concentrations between about 0.03 and about 0.07 weight percent are also useful.

Another additive which was determined, quite unexpectedly, to enhance the preservative effectiveness of formulations containing docosanoid active agents is mannitol, which is a known tonicity adjuster. Other non-ionic tonicity-adjusting agents, such as other simple sugars, can perform the same function.

Thus, use of one or more preservative enhancers can provide at least two advantages. First, the amount of strong preservative, which may cause irritation to some patients, required for a given level of preservation is reduced. Second, the preservative enhancers may be chosen so that they serve functions in addition to improving preservation of the formulation.

An additional weaker preservative may be added to the formulation. The weaker preservative, at the concentrations of use, should not be sufficiently potent to cause irritation of the target tissue, which the solution will contact. Examples of weaker preservatives useful in accordance with the present invention include, without limitation thereto, peroxides, such as hydrogen peroxide; peroxide-generating species, such as an alkali perborate or a combination of sodium perborate, boric acid, and sodium borate; urea peroxide; sodium peroxide carbonate; sodium persulfate; sodium perphosphate; and poly(vinyl pyrrolidone) hydrogen peroxide. A preferred weak preservative is a perborate such as sodium perborate.

If a peroxide or peroxide-generating species is used, the peroxide concentration should be less than about 0.1 weight percent, e.g., between about 0.004 and about 0.05 weight percent, or, e.g., between about 0.001 to 0.02 weight percent.

The addition of a buffer offers at least two advantages. First, the buffer helps maintain the pH of the formulation at an ophthalmically acceptable level for instillation directly into the eye. Second, incorporating a buffer early in the manufacturing process reduces the complexity of controlling the pH during manufacturing.

A variety of ophthalmically acceptable buffers may be used, e.g., borate buffers, such as a combination of boric acid and sodium borate, phosphate buffers, citrates, lactates, equivalents thereof and mixtures thereof.

Also, as mentioned above, EDTA, which is a useful weak preservative, may serve a buffering function. Thus, EDTA can be used to adjust and maintain the pH and to act as a preservative enhancer. EDTA may further serve as a stabilizer for the active agent, i.e., may inhibit degradation of the active agent (e.g., by chelating metal ions which may catalyze degradation or acting as an antioxidant).

Tonicity adjusting agents may be added to the ophthalmic compositions in order to improve ophthalmic compatibility, i.e., to adjust tonicity to approximate that of tears. A wide variety of tonicity adjusting agents may be used. Useful ophthalmic tonicity adjusting agents include, without limitation, sodium chloride, mannitol, benzalkonium chloride, phedrine chloride, procaine chloride, chloramphenicol, sodium citrate, mixtures thereof or the like.

However, non-ionic tonicity adjusting agents are most useful for maximizing the solubility of the non-ionic docosanoid. Examples of useful non-ionic tonicity adjusting agents include mannitol, sorbitol, glycerol, polyethylene glycols, polypropylene glycols, sorbitol and mixtures thereof.

In addition to the unexpected enhancement of preservative effectiveness, certain non-ionic tonicity adjusting agents may serve additional functions in ophthalmic formulations containing docosanoid active agents. For example, it has been unexpectedly discovered that mannitol increases the solubility of isopropyl unoprostone. Thus, use of appropriate non-ionic tonicity adjusting agents can (1) result in lower requirements for strong preservatives which may cause ocular irritation, (2) reduce the concentration of solubility enhancers and/or reduce the amount of active agent required to achieve a chosen active agent concentration in solution, and (3) adjust the tonicity to ophthalmically acceptable levels.

The tonicity adjusting agent concentration is typically determined by adding sufficient tonicity adjusting agent to produce a formulation with is substantially isotonic, in order to maximize patient comfort. An isotonic solution is one which may be expressed as having a concentration equivalent to about 0.9 mg/ml sodium chloride in deionized water. Substantially isotonic, as used herein, refers to a formulation having between about 0.8 and about 1.0 mg/ml NaCI equivalents.

In order to achieve a substantially isotonic solution, between about 0.1 and about 10 weight percent of non-ionic tonicity adjusting agent can be added to the formulation. Another suitable range is between about 1 and about 7 weight percent of non-ionic tonicity adjusting agent. Another suitable range is between about 3 and about 5 weight percent of non-ionic tonicity adjusting agent.

Water is a useful solvent for the present invention in the form, e.g., of distilled water or physiological saline. However, the invention is not limited to a particular solvent or diluent, except that the solvent must be ophthalmically compatible under the conditions of intended use. Other examples of diluents for producing a non-aqueous suspension include, without limitation, edible oils, liquid paraffins, mineral oil, propylene glycol, p-octyldodecanol, mixtures thereof and the like.

While the docosanoid formulations described herein are useful in treating diabetic retinopathy without additional active ingredients, formulations with additional active ingredients are within the scope of the invention. For example, the present formulations may include conventional cholinergic ocular hypertensive agents such as pilocarpine or carbenzalkonium chloridehol; anticholinesterases such as demecarium, D.F.P. (Diflupyl) or echothiophate; miotics such as physostigmine salicylate or pilocarpine hydrochloride; and antiinflammatories such as diclofenac, penicillin, sulfonamide, chloramphenicol, cortisone or chlorpheniramine.

The aforementioned actives are listed to further the reader's understanding of the various embodiments of the invention. Thus, the list of actives, provided above for addition to the present formulations, is not exhaustive and the invention is not so limited.

The ophthalmic compositions of the invention may be applied to the ocular tissue or ocular fluids via a number of techniques. For example, a solution or slurry of the ophthalmic composition may be directly instilled into the eye in a droplet, spray, or mist form. Alternatively, a drug delivery device comprising a reservoir, such as a network of polymers or a cross-linked polymer, which holds the ophthalmic composition, may be inserted into the ocular cavity (e.g., under the eyelid) and left for an extended period of time. The compositions may also be applied transdermally, including by electrotransport, preferably to skin areas near the eye. Injection, either subcutaneous or intraocular, and oral administration may also be useful delivery routes.

When a composition of the invention is applied topically, dropwise, to the eye, the number of drops and number of applications per day may vary, depending, inter alia, on the composition efficacy, patient tolerance and relative state of the disease. Typical useful drop volumes are from between about 10 to about 50 μl, between about 15 and about 45 μl, between about 20 and about 40 μl, or between about 25 and 35 μl. Application frequency can be, without limitation, once a day, twice a day, three times a day, or four times a day. Administration, once initiated, can continue for as long as a diabetic patient is at risk for diabetic retinopathy. Other administration regimens may be found to be suitable for particular patients in the treatment of diabetic retinopathy.

Example 1

Ischemic retinopathy is produced in C57/BL6J mice. Seven-day-old mice and their mothers are placed in an airtight incubator and exposed to an atmosphere of 75.± 0.3% oxygen for 5 days. Incubator temperature is maintained at 23 ± 0.2.°C, and oxygen is measured every 8 hours with an oxygen analyzer. After 5 days, the mice are removed from the incubator, placed in room air, and subjected to drug treatment. The U.S. marketed formulation of Ul 0.15% is administered topically to the mice's eyes. As a control, a group of mice are given the vehicle for Ul (unoprostone isopropyl).

After 5 days of treatment, the mice are sacrificed, eyes are rapidly removed and frozen in optimum cutting temperature embedding compound (OCT; Miles Diagnostics, Elkhart, IN) or fixed in 10% phosphate-buffered formalin and embedded in paraffin. Adult C57BL6J mice are also treated by administration of drug or vehicle and after 5 days, they are sacrificed and their eyes are processed for frozen or paraffin sections.

Frozen sections (10 μm) of the eyes from drug-treated and control mice are histochemically stained with biotinylated griffonia simplicifolia lectin B4 (Vector Laboratories, Burlingame, Calif.) which selectively binds to endothelial cells. Slides are incubated in methanol/H₂O₂ for 10 minutes at 4 °C, washed with 0.05 M Tris-buffered saline, pH 7.6 (TBS), and incubated for 30 minutes in 10% normal porcine serum. Slides are incubated 2 hours at room temperature with biotinylated lectin and after rinsing with 0.05M TBS, they are incubated with avidin coupled to peroxidase (Vector Laboratories) for 45 minutes at room temperature. After being washed for 10 minutes with 0.05 M TBS, slides are incubated with diaminobenzidine to give a brown reaction product. Some slides are counterstained with hematoxyln and all are mounted with Cytoseal.

To perform quantitative assessments, 10 μm serial sections are cut through half of each eye and sections roughly 50-60 μm apart are stained with lectin, providing 13 sections per eye for analysis. Lectin-stained sections are examined with an Axioskop microscope (Zeiss, Thornwood, N.Y.) and images are digitized using a 3 CCD color video camera (IK- TU40A, Toshiba, Tokyo, Japan) and a frame grabber. Image-Pro Plus software (Media Cybernetics, Silver Spring, Md.) is used to delineate lectin-stained cells on the surface of the retina and their area is measured. The mean of the measurements from each eye is used as a single experimental value.

The mice with ischemic retinopathy treated with the vehicle without Ul show an increase in the area of endothelial cell staining throughout the retina when compared to nonischemic mice. Ischemic mice that are given Ul twice a day have a decrease in endothelial cell staining on the surface and within the retina when compared to the vehicle- treated mice. The results demonstrate that isopropyl unoprostone inhibits retinal neovascularization.

Example 2

To test the effect of unoprostone isopropyl on development of diabetic retinopathy, an animal model which demonstrates symptoms of preproliferative diabetic retinopathy is selected. The Zucker Diabetic Fatty (ZDF) rats are a non-insulin dependent model of diabetes mellitus. The animals develop increased retinal capillary basement membrane thickening and retinal capillary cell density indicative of early proliferative retinopathy by six months of age.

ZDF rats and heterozygous nondiabetic Zucker control rats are treated twice daily with Ul (0.15%) or placebo eye drops for 6 months starting at 1 month of age. Retinal capillary basement membrane thickening is determined from transmission electron microscopy and retinal capillary cell density is measured from trypsin digest preparations according to methods set out in Yang, Danis, Peterson, Dolan and Yu, J Ocul. Pharmacol. Ther. 2000 Oct: 16(5): 471-9. Placebo-treated ZDF rats have thicker retinal basement membrane of about 40% and increased capillary cell density of about 20% compared to Ul-treated rats and treated or untreated controls. There is no significant difference between the animals treated with Ul and the controls.

The development of symptoms of preproliferative diabetic retinopathy is prevented by the administration of topical Ul.

Example 3

Diabetic patients are treated with Ul or placebo in a randomized, two period crossover with a one month washout between periods. Non-diabetic patients are also studied. Mean circulation time in the retina is measured at baseline, after the first dose (4 drops) and after 28 days of twice daily dosing. Retinal blood flow and IOP are determined at the same time of day for a specific patient.

Patients are at least 18 years old, not pregnant or planning to become pregnant during the study. Diabetic patients must have been diagnosed with diabetes mellitus within the last 10 years, must not have proliferative or non-proliferative retinopathy and must have HbA1c between 8 and 12%. All subjects have resting diastolic blood pressure of between 75 and 90 mm Hg and systolic blood pressure less than 159 mm Hg. IOP is less than 20 mmHg, and if the subject is on medications, must remain on the same dose for the duration of the study.

The U.S. marketed formulation of Rescula® unoprostone isopropyl (0.15%) is administered topically. On the first day, after the baseline assessments are performed, the patients are given one drop to each eye at 30-minute intervals for a total of 4 drops per eye. Following the study assessments, the patient administers a single drop to each eye at 12 hour intervals thereafter. An identically packaged placebo solution is administered in a masked fashion. All patients receive both treatments and are randomly assigned to the order of treatments.

Each treatment is administered for 28 days with a 28 day washout between treatments.

The primary efficacy variable is the change from baseline in the mean circulation time as measured from video fluorescein angiograms. Retinal blood flow measurements are determined from video recordings of fluorescein dye passage through the retinal circulation. An antecubital vein catheter is used to introduce a bolus of fluorescein dye. A 0.75 μl bolus of 10% sodium fluorescein dye is rapidly injected to ensure a sharp dye front in the retinal vasculature. A fluorescein angiogram is obtained from both eyes of each patient. A scanning laser ophthalmoscope is used to image the retina, and the video images are directly digitized and are stored at 30 frames per second. The digitized video images are computer analyzed on a frame-by-frame basis. Image analysis is performed on the four major retinal artery/vein pairs exiting from the optic disc and perfusing the four retinal quadrants. Measurement of retinal vessel diameters and retinal vessel fluorescence intensities are performed at a fixed radial distance from the center of the optic disc. The resulting vessel fluorescence intensity curves are fit to a lognormal distribution function, and the fitted parameters are used to calculate the mean circulation time (MCT) for each quadrant. The calculated retinal blood flow for each quadrant is proportional to the sum of the squares of the artery and vein diameters divided by the MCT for that artery/vein pair. Final values for retinal vessel diameters, MCT, and blood flow represent the average of all four individual quadrants. The primary efficacy time point is the change from baseline after 28 days of treatment.

It is found that treatment of diabetics with Ul can increase the reduced (relative to non-diabetic controls) retinal blood flow observed in untreated diabetics. That is, retinal blood flow, as assessed by the mean circulation time by video fluorescein angiography, is increased in diabetics by the topical ocular administration of Ul.

Accordingly, the invention further relates to the use of a docosanoid in the preparation of a medicament, in particular a topical medicament for the topical administration of a docosanoid to the eye, for the treatment of diabetic complications of the eye, wherein said complication is selected from the group of retinal neovascularization, diabetic retinopathy, preproliferative diabetic retinopathy and retinal blood flow. Preferably, a docosanoid, in particular isopropyl unoprostone, may be used to treat diabetic retinopathy, also preferably preproliferative diabetic retinopathy.

Claims

1. Use of a docosanoid in the preparation of a medicament, in particular a topical medicament for the topical administration of a docosanoid to the eye, for the treatment of diabetic complications of the eye, wherein said complication is selected from the group of retinal neovascularization, diabetic retinopathy, preproliferative diabetic retinopathy and retinal blood flow.

2. Use of claim 1 , wherein said docosanoid is isopropyl unoprostone.

3. Use of claim 1 , wherein said topical medicament contains isopropyl unoprostone in a concentration of 0.001 to 0.30 weight percent, preferably in a concentration of 0.06 to 0.24 weight percent, more preferably in a concentration of 0.10 and 0.20 weight percent, in particular in a concentration of 0.12 weight percent and also in particular in a concentration of 0.15 weight percent.

4. Use of claim 1 , wherein said complication is retinal neovascularization, diabetic retinopathy, and preproliferative diabetic retinopathy.

5. Use of claim 1 , wherein said complication is retinal neovascularization, and diabetic retinopathy, preferably diabetic retinopathy.

6. A method for protecting the vision of a human suffering from diabetes comprising administering to a human suffering from diabetes an effective amount of a composition comprising a docosanoid active agent effective to increase the retinal bloodflow of the human.

7. The method of claim 6, wherein the human is suffering from type I diabetes or type II diabetes.

8. The method of claim 6, wherein the docosanoid active agent is unoprostone isopropyl.

9. The method of claim 6, wherein the composition is administered topically to the eye.

10. The method of claim 6, wherein the composition is administered once a day, twice a day, three times a day, or four times a day.

11. The method of claim 6, wherein the unoprostone isopropyl is present in the composition at a concentration of about 0.12% or about 0.15%.

12. The method of claim 6 wherein the administration comprises inserting a reservoir device comprising said docosanoid into the eye cavity.

13. Method of claim 6, wherein protecting the vision of a human suffering from diabetes refers to the inhibition of the formation of new blood vessels in the retina.

14. A method of inhibiting at least one of increased retinal capillary basement membrane thickening and retinal capillary cell density, wherein said increased retinal capillary basement membrane thickening and retinal capillary cell density are indicative of early proliferative retinopathy in a human suffering from diabetes, comprising administering to a human suffering from diabetes an amount of a composition comprising a docosanoid active agent effective to inhibit at least one of increased retinal capillary basement membrane thickening and retinal capillary cell density indicative of early proliferative retinopathy.

15. The method of claim 14 wherein the administration comprises inserting a reservoir device comprising unoprostone isopropyl into the eye cavity.

16. Use of claim 1 , wherein said diabetic complications of the eye is in a human suffering from type I diabetes or type II diabetes.