METHOD FOR STABILIZING THE pH OF AN AQUEOUS COMPOSITION COMPRISING A DRUG

Abstract

This description relates to a method for stabilizing the pH of an aqueous composition comprising a drug that is prone to oxidation, said method comprising the addition of an additive to prevent the oxidation of the drug that is prone to oxidation; in particular, this description relates to a method for stabilizing the pH of an aqueous composition comprising a corticosteroid, said method comprising the addition of an additive to prevent the oxidation of the corticosteroid; this description also relates to a composition comprising a corticosteroid and an additive to prevent the oxidation of the corticosteroid.

Description

This description relates to a method for stabilizing the pH of an aqueous composition comprising a drug, said method comprising the addition of an additive to prevent oxidation of the drug. In particular, this description relates to a method for stabilizing the pH of an aqueous composition comprising a corticosteroid, said method comprising the addition of an additive to prevent oxidation of the corticosteroid. This description also relates to a composition comprising a corticosteroid and an additive to prevent oxidation of the corticosteroid. BACKGROUND OF THE INVENTION Eye conditions are a global problem: an estimated 285 million people worldwide have a visual impairment. In the U.S., 2.1 million Americans are diagnosed with age-related macular degeneration (AMD), 2.7 million with glaucoma, 7.7 million with diabetic retinopathy, and 24 million with cataracts. Most eye conditions can be treated and / or controlled to reduce negative effects, including total blindness. However, current treatments for eye conditions are limited by the difficulty of delivering effective doses of drugs to the target tissues of the eye. In current treatments, topical administration of eye drops is the preferred method of drug delivery to the eye due to the convenience and safety of eye drops compared to other ophthalmic drug delivery routes, such as intravitreal injections and implants (Le Souriais, C., Acar, L., Zia, H., Sado, PA, Needham, T., Leverge, R., 1998. Ophthalmic drug delivery systems-Recent advances. Progress in Retinal and Eye Research 17, 33-58).Drugs are transported primarily by passive diffusion from the surface of the eye into the eye and surrounding tissues where, according to Fick's law, the drug is driven into the eye by the gradient of dissolved drug molecules. Passive drug diffusion in the eye is hampered by three main obstacles (Gan, L., Wang, 1, Jiang, M., Bartlett, H., Ouyang, D., Eperjesi, F., Liu, 1, Gan, Y., 2013. Recent advances in topical ophthalmic drug delivery with lipid—based nanocarriers. Drug Discov. Today 18, 290-297; Loftsson, T., Sigurdsson, HH, Konradsdottir, F., Gisladottir, S., Jansook, P., Stefansson, E., 2008. Topical drug delivery to the posterior segment of the eye: anatomical and iviA / a / zuzi / uio / o / physiological considerations. Pharmazie 63, 171-179; drug delivery. Adv. Drug Del. Rev. 58, 1131-1135). Recently, the applicants have described the preparation and testing of cyclodextrin-based eye drops containing dexamethasone (WO2018 / 100434, Johannesson, G., Moya-Ortega, MD, Asgrimsdottir, GM, Lund, SH, Thorsteinsdottir, M., Loftsson, T., Stefansson, E., 2014. Kinetics of γ-cyclodextrin nanoparticle suspension eye drops in tear fluid. Acta Ophthalmologica 92, 550-556; Thorsteinn Loftsson and Einar Stefansson, Cyclodextrin nanotechnology for ophthalmic drug delivery, U.S. Patent No. 7,893,040 (February 22, 2011); Thorsteinn Loftsson and Einar Stefansson, Cyclodextrin nanotechnology for ophthalmic drug delivery, U.S. Patent No. 8,633,172 (January 21, 2014); Thorsteinn Loftsson and Einar Stefansson, Cyclodextrin nanotechnology for ophthalmic drug delivery U.S. Patent No. 8,999,953 (April 7, 2015). These studies show that cyclodextrin-based eye drops containing the active ingredient are promising for the treatment of eye conditions. However, under certain storage conditions, such as when stored in low-density polyethylene (LDPE) vials for several months, the pH of cyclodextrin-based eye drops containing the active ingredient is unstable and decreases over a prolonged period. Therefore, it is desirable to develop a method to stabilize the pH of these aqueous compositions to prevent this pH drop. BRIEF DESCRIPTION OF THE INVENTION A first objective of the present description is a method for stabilizing the pH of an aqueous composition comprising a drug, said method comprising the addition of an additive to prevent oxidation of the drug. The inventors have surprisingly discovered that adding an additive to prevent oxidation of the drug to the aqueous solution can prevent the pH from dropping, especially during long periods of storage. A second objective of the present description is an aqueous composition comprising a corticosteroid, cyclodextrin and an additive for preventing oxidation of the corticosteroid, wherein said additive is present in the composition at a concentration between 0.15% (w / v) and 0.6% (w / v), for example between 0.15% (w / v) and 0.45% (w / v), and preferably at a concentration between 0.2% (w / v) and 0.4% (w / v). A third objective of the present description is the use of an additive to prevent the oxidation of a corticosteroid to stabilize the pH of an aqueous composition comprising a corticosteroid. A fourth objective of the present description is a method for stabilizing the pH of an aqueous composition comprising a drug, said method comprising the use of an oxygen absorber to prevent oxidation of the drug. DETAILED DESCRIPTION OF THE INVENTION Definitions As used herein, the term % by weight of a compound X based on the volume of the composition, also abbreviated as % w / v, corresponds to the amount of compound X in grams that is introduced into 100 ml of the composition. As used herein, an eye condition is a disease, ailment, or other condition that affects or involves the eye, one of the parts or regions of the eye, or surrounding tissues such as the lacrimal glands. Generally speaking, the eye includes the eyeball and the tissues and fluids that constitute the eyeball, the periocular muscles (such as the oblique and rectus muscles), the portion of the optic nerve that is within or adjacent to the eyeball, and surrounding tissues such as the lacrimal glands and eyelids. As used herein, an anterior eye condition is a disease, ailment, or condition that affects or involves an anterior ocular region or site (i.e., the front of the eye), such as a periocular muscle, eyelid, lacrimal gland, or eyeball tissue or fluid that lies anterior to the posterior wall of the lens capsule or ciliary muscles. Therefore, an anterior ocular condition primarily affects or involves one or more of the following: the conjunctiva, cornea, anterior chamber, iris, lens or lens capsule, and the blood vessels and nerves that vascularize or innervate an anterior ocular site or region. An anterior ocular condition is also considered here to extend to the lacrimal apparatus. In particular, the lacrimal glands that secrete tears, and their excretory ducts that transport lacrimal fluid to the surface of the eye. In addition, an anterior eye condition affects or involves the posterior chamber, which is located behind the retina but in front of the back wall of the lens capsule. An anterior eye condition includes a disease, ailment, or condition such as, for example, aphakia; pseudophakia; astigmatism; blepharospasm; cataract; conjunctival diseases; conjunctivitis; corneal diseases; corneal ulcer; dry eye syndromes; eyelid diseases; lacrimal apparatus diseases; lacrimal duct obstruction; myopia; presbyopia; pupillary disorders; refractive errors; and strabismus. Glaucoma can also be considered an anterior eye condition because a clinical goal of glaucoma treatment can be to reduce the aqueous humor in the anterior chamber of the eye (i.e., to lower intraocular pressure). Previous eye conditions also include inflammations in the front of the eye, such as inflammation after cataract surgery, glaucoma, anterior chamber inflammation, and central macular edema. A posterior eye condition is a disease, ailment, or condition that primarily affects or involves a posterior ocular region or site, such as the choroid or sclera (in a position posterior to a plane through the posterior wall of the lens capsule), vitreous, vitreous chamber, retina, optic nerve (i.e., the optic disc), and blood vessels and nerves that vascularize or innervate a posterior ocular region or site. Therefore, a posterior ocular condition may include a disease, ailment, or condition such as, for example, macular degeneration (such as non-exudative age-related macular degeneration and exudative age-related macular degeneration); choroidal neovascularization; acute macular neuroretinopathy; macular edema (such as cystoid macular edema and diabetic macular edema); Behcet's disease; retinal disorders; diabetic retinopathy (including proliferative diabetic retinopathy); retinal arterial occlusive disease; central retinal vein occlusion (CRVO); uveitic retinal disease; retinal detachment; ocular trauma affecting a posterior ocular site or location; a posterior ocular condition caused or influenced by ocular laser treatment; posterior ocular conditions caused or influenced by photodynamic therapy; photocoagulation; radiation retinopathy; epiretinal membrane disorders;Retinal vein branch occlusion; anterior ischemic optic neuropathy; diabetic retinal dysfunction (non-retinopathy), retinitis pigmentosa, and glaucoma. Glaucoma can be considered a posterior ocular condition because the therapeutic goal is to prevent or reduce the occurrence of vision loss due to damage to or loss of retinal or optic nerve cells (i.e., neuroprotection). As used herein, the term microparticle refers to a particle having a diameter Dso of approximately 1 pm to approximately 200 pm. The term nanoparticle refers to a particle having a diameter Dso of less than 1 pm. In exemplary embodiments, the diameter, which may be Dso, is 1 pm or greater to approximately 200 pm; and the term nanoparticle refers to a particle having a Dso of less than approximately 1 pm. The term microsuspension is intended to mean a composition comprising complex solid microparticles suspended in a liquid phase. As used herein, the expression to prevent drug oxidation is intended to mean to prevent or delay the oxidation of the drug. Method for stabilizing the pH of an aqueous composition comprising a drug. This description first relates to a method for stabilizing the pH of an aqueous composition comprising a drug, said method comprising the addition of an additive to prevent oxidation of the drug. The description also relates to an aqueous composition comprising a drug and an additive to prevent oxidation of the drug obtained by this method. The additive to prevent drug oxidation can be added to the aqueous composition before or after the drug. Drug The aqueous composition of the disclosure comprises a drug. In the context of the disclosure, the drug is an ophthalmic drug, that is, a compound that exhibits a therapeutic effect when administered in a sufficient quantity to a patient suffering from an eye condition. In one formulation, the drug is a corticosteroid, which includes glucocorticoids and mineralocorticoids. Advantageously, the drug is selected from betamethasone-type corticosteroids, which are glucocorticoids with a Ci6 methyl substitution. Betamethasone-type corticosteroids include alclomethasone, beclomethasone, betamethasone, clobetasone, clocortolone, desoximethasone, dexamethasone, diflucortolone, flumethasone, fluocortolone, fluprednidene, fluticasone, halomethasone, and mometasone. Preferably, the drug is dexamethasone. In a specific formulation, the drug is prone to oxidation, meaning it can be degraded through an oxidation pathway. In some cases, the degradation products of this oxidation are acidic degradation products, and adding an additive to prevent drug oxidation prevents the formation of these acidic degradation products. The concentration of the drug in the aqueous composition described may be from approximately 0.1 mg / ml to approximately 100 mg / ml, specifically from approximately 1 mg / ml to approximately 100 mg / ml, particularly from approximately 1 mg / ml to approximately 50 mg / ml, more specifically from approximately 1 mg / ml to approximately 40 mg / ml, even more specifically from approximately 5 mg / ml to approximately 35 mg / ml, and still more specifically from approximately 10 mg / ml to approximately 30 mg / ml. The concentration of the drug in the aqueous composition described may be from approximately 5 mg / ml to approximately 30 mg / ml, specifically from approximately 10 mg / ml to approximately 25 mg / ml. The amount of drug in the aqueous composition can be from 0.5 to 5%, particularly from 1 to 4%, and more particularly from 1.5 to 3%, by weight of drug based on the volume of the composition. Cyclodextrin The aqueous composition may include cyclodextrin. The amount of cyclodextrin in the aqueous composition may be from 1 to 35%, particularly from 5 to 30%, more particularly from 10 to 27%, and even more particularly from 12 to 25%, by weight of cyclodextrin relative to the volume of the composition. Cyclodextrins are cyclic oligosaccharides containing 6 (α-cyclodextrin), 7 (β-cyclodextrin), and 8 (γ-cyclodextrin) glucopyranose monomers linked by α-1,4-glycosidic bonds. α-Cyclodextrin, β-cyclodextrin, and γ-cyclodextrin are naturally occurring products formed by the microbial degradation of starch. The outer surface of ring-shaped cyclodextrin molecules is hydrophilic, with numerous hydroxyl groups, but their central cavity is somewhat lipophilic (Kurkov, SV, Loftsson, T., 2013. Cyclodextrins. Int J Pharm 453, 167-180; Loftsson, T., Brewster, M. E., 1996. Pharmaceutical applications of cyclodextrins. 1. Drug solubilization and stabilization. Journal of Pharmaceutical Sciences 85, 1017-1025). In addition to the three naturally occurring cyclodextrins, numerous water-soluble cyclodextrin derivatives have been synthesized and tested as drug carriers, including cyclodextrin polymers (Stella, VJ, He, Q., 2008. Cyclodextrins. Tox.Pathol. 36, 30-42). Cyclodextrins can improve the solubility and bioavailability of hydrophobic compounds. In aqueous solutions, cyclodextrins form inclusion complexes with many drugs by adsorbing a drug molecule, or more frequently, a lipophilic fragment of the molecule, into their central cavity. This property has been used for drug formulation and delivery. The formation of drug / cyclodextrin inclusion complexes, their effect on the physicochemical properties of drugs, their effect on the ability of drugs to penetrate biomembranes, and the use of cyclodextrins in pharmaceuticals have been reviewed (Loftsson, T., Brewster, ME, 2010. Pharmaceutical applications of cyclodextrins: basic science and product development. Journal of Pharmacy and Pharmacology 62, 1607-1621; Loftsson, T., Brewster, ME, 2011. Pharmaceutical applications of cyclodextrins: effects on drug permeation through biological membranes. J. Pharm.Pharmacol. 63, 1119-1135; Loftsson, T., Jarvinen, T., 1999. Cyclodextrins in ophthalmic drug delivery. Advanced Drug Delivery Reviews 36, 59-79). Cyclodextrins and drug / cyclodextrin complexes can self-assemble in aqueous solutions to form nano- and micro-sized aggregates and micellar-like structures that can also solubilize poorly soluble drugs through non-inclusion complexation and micellar-like solubilization (Messner, M., Kurkov, SV, Jansook, P., Loftsson, T., 2010. Self-assembled cyclodextrin aggregates and nanoparticles. Int J Pharm 387, 199-208). In general, the tendency of cyclodextrins to self-assemble and form aggregates increases with the formation of drug / cyclodextrin complexes, and aggregation increases with increasing concentration of these complexes. MA / a / ZUZl / UlD / Of drug / cyclodextrin. In general, hydrophilic cyclodextrin derivatives, such as 2-hydroxypropyl-βcyclodextrin and 2-hydroxypropyl-γ-cyclodextrin, and their complexes are freely soluble in water. On the other hand, natural α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin and their complexes have a limited solubility in pure water or 129.5 ± 0.7, 18.4 ± 0.2 and 249.2 ± 0.2 mg / ml, respectively, at 25°C (Sabadini E., Cosgrovea T. and do Carme Egidio F., 2006. Solubility of cyclomaltooligosaccharides (cyclodextrins) in HzO and D2O: a comparative study. Carbohydr Res 341, 270-274). It is known that their solubility increases somewhat with increasing temperature (Jozwiakowski, M. J., Connors, K. A, 1985. Aqueous solubility behavior of three cyclodextrins. Carbohydr. Res., 143, 51-59). Due to the limited solubility of their complexes, natural cyclodextrins more frequently exhibit Bs-type or B1-type phase solubility diagrams (Brewster M. E.Loftsson T., 2007, Cyclodextrins as pharmaceutical solubilizers. Adv. Drug Deliv. Rev., 59, 645-666). It has been observed that the solubility of natural cyclodextrins can decrease below their solubility in pure water after the formation of drug / cyclodextrin complexes (Jansook, P., Maya-Ortega, MD, Loftsson, T., 2010. Effect of self-aggregation of γ-cyclodextrin on drug solubilization. Journal of Inclusion Phenomena and Macrocyclic Chemistry 68, 229-236). The low concentration of dissolved drug / cyclodextrin complexes hinders the formation of drug / cyclodextrin complexes containing nano- and microparticles. In addition, other excipients, such as water-soluble polymers used to stabilize nano- and micro-suspensions, can form complexes with cyclodextrins and thus further hinder the formation of drug / cyclodextrin complexes. Previously, the applicants have described the preparation and testing of cyclodextrin-based eye drops containing dexamethasone (Johannesson, G., Moya-Ortega, MD, Asgrimsdottir, GM, Lund, SH, Thorsteinsdottir, M., Loftsson, T., Stefansson, E., 2014. Kinetics of y-cyclodextrin nanoparticle suspension eye drops in tear fluid. Acta Ophthalmologica 92, 550-556; Thorsteinn Loftsson and Einar Stefansson, Cyclodextrin nanotechnology for ophthalmic drug delivery, U.S. Patent No. 7,893,040 (February 22, 2011); Thorsteinn Loftsson and Einar Stefansson, Cyclodextrin nanotechnology for ophthalmic drug delivery, U.S. Patent No. 8,633,172 (January 21, 2012). 2014); Thorsteinn Loftsson and Einar Stefansson, Cyclodextrin nanotechnology for ophthalmic drug delivery US Patent No. 8,999,953 (April 7, 2015)), dorzolamide (Johannesson, G., Maya-Ortega, MD, Asgrimsdottir, GM, Lund, SH, Thorsteinsdottir, M., Loftsson, T., Stefansson, E., 2014. Kinetics of γ-cyclodextrin nanoparticle suspensión eye drops in tear fluid. Acta Ophthalmologica 92, 550-556; Gudmundsdottir, B.S., Petursdottir, D., Asgrimsdottir, G.M., Gottfredsdottir, M.S., Hardarson, S.H., Johannesson, G., Kurkov, S.V., Jansook, P., Loftsson, T., Stefansson, E., 2014. y-Cyclodextrin nanoparticle eye drops with dorzolamide: effect on ¡ntraocular pressure in man. J. Ocul. Pharmacol. Ther. 30, 35-41), irbesartan (Muankaew, C., Jansook, P., Stefansson, E., Loftsson, T., 2014. Effect of ycyclodextrin on solubilization and complexation of irbesartan: influence of pH and excipients. Int J Pharm. ΜΛ / a / ZUZl / U 1 Oí Oí 474, 80-90), telmisartan (C. Muankaew, P. Jansook, H. H. Sigurósson, T. Loftsson, 2016, Cyclodextrin-based telmisartan ophthalmic suspension: Formulation development for water-insoluble drugs. Int. J. Pharm. 507, 21-31) and cyclosporine A (S. Jóhannsdóttir, P. Jansook, E. Stefansson, T. Loftsson, 2015, Development of a cyclodextrin-based aqueous cyclosporin A eye drop formulation. Int. J. Pharm. 493(12), 86-95) in cyclodextrin nanoparticles. Studies show that the nanoparticles increase the contact time of the drug with the ocular surface and the ocular bioavailability of the drugs. Drug / cyclodextrin nanoparticles and microparticles not only retain on the surface of the eye but also improve the solubility of the drug in the aqueous tear fluid.Nanoparticles and microparticles composed of drug / γ-cyclodextrin complexes have been shown to be particularly effective drug carriers for topical drug delivery to the eye. The disclosure may comprise a solid complex consisting of a drug and a cyclodextrin. The complex comprising a drug and a cyclodextrin may be referred to as the drug / cyclodextrin complex. When the drug is a corticosteroid, the complex comprising a corticosteroid and a cyclodextrin may be referred to as the corticosteroid / cyclodextrin complex. When the drug is dexamethasone and the cyclodextrin is γ-cyclodextrin, the complex comprising dexamethasone and γ-cyclodextrin may be referred to as the dexamethasone / γ-cyclodextrin complex. The solid complex of the disclosure composition may be a complex aggregate. The complex aggregate may correspond to an aggregate of a plurality of complexes, in particular a plurality of inclusion complexes comprising a drug and a cyclodextrin, typically complexes comprising a drug and γ-cyclodextrin. According to one modality, the aqueous composition of the description is a microsuspension. Specifically, the aqueous composition described comprises a solid complex having a diameter Dso of less than approximately 100 pm, specifically from approximately 1 pm to approximately 100 pm. In one embodiment, the diameter Dso may be in the range of approximately 1 pm to approximately 25 pm, specifically from approximately 1 pm to approximately 20 pm, more specifically from approximately 1 pm to approximately 10 pm, even more specifically from approximately 2 pm to approximately 10 pm, and still more specifically from approximately 2 pm to approximately 5 pm or from approximately 3 pm to approximately 8 pm. The diameter and / or size of a particle or complex may be measured according to any method known to those skilled in the art. For example, the diameter Dso is measured by laser diffraction particle size analysis.Generally, there are a limited number of techniques for measuring / evaluating cyclodextrin / drug particle or complex diameter and / or size. In particular, those skilled in this field know that physical properties (e.g., particle size, diameter, average diameter, mean particle size, etc.) are typically evaluated / measured using such limited and typical known techniques. For example, such known techniques are described in Int. J. Pharm. 493 (2015), 86-95, which is incorporated herein by reference in its entirety. Furthermore, such limited known measurement / evaluation techniques were known in the art, as demonstrated by other technical references such as, for example, the European Pharmacopoeia (2.9).31 Particle size analysis by laser diffraction, January 2010) and Saurabh Bhatia, Nanoparticles types, classification, characterization, manufacturing methods and drug delivery applications, Chapter 2, Drug delivery systems with natural polymers, pp. 33-94, Springer, 2016, which are also incorporated herein by reference in their entirety. The European Pharmacopoeia (01 / 2008: 1163) states that eye drops in suspension form must comply with the following: for every 10 pg of solid active substance, no more than approximately 20 particles have a maximum dimension greater than approximately 25 pm, and no more than approximately 2 of these particles have a maximum dimension greater than approximately 50 pm. None of the particles may have a maximum dimension greater than approximately 90 pm. The aqueous compositions disclosed herein are in accordance with the requirements of the European Pharmacopoeia (01 / 2008: 1163). In general, it is recommended that particle sizes in aqueous suspensions for eye drops be kept to a minimum, preferably below approximately 10 µm, to avoid eye irritation. Furthermore, the settling rate in aqueous suspensions is proportional to the particle diameter; the settling rate of larger particles is faster than that of smaller particles, assuming all other factors remain constant. In particular, 60 to 95% by weight, more particularly 70 to 90% by weight, of the drug in the composition may be in the form of a solid complex of drug and cyclodextrin. More specifically, 5 to 40% by weight, and particularly 10 to 30% by weight, of the drug in the composition may be in dissolved form. The dissolved form includes non-complexed drug that dissolves in the liquid phase and drug-cyclodextrin complexes that dissolve in the liquid phase, as well as water-soluble nanoparticles consisting of complex drug / cyclodextrin aggregates. Preferably, 0% to 0.5% by weight of the drug in the composition may be in uncomplexed solid form. As such, the composition of the disclosure may be substantially free of uncomplexed solid drug particles. In one embodiment, the microsuspension may comprise approximately 70% to approximately 99% of the drug in microparticles and approximately 1% to approximately 30% of the drug in nanoparticles. More specifically, the microsuspension may comprise approximately 80% to approximately 95% of the drug in microparticles having a diameter of approximately 1 µm to approximately 10 µm, and approximately 20% to approximately 5% of the drug in nanoparticles. Alternatively, the microsuspension may comprise approximately 80% of the drug in microparticles having a diameter of approximately 1 µm to approximately 10 µm, and approximately 20% of the drug in nanoparticles. In another embodiment, the microsuspension may comprise approximately 40% to approximately 99% of the drug in microparticles and approximately 1% to approximately 60% of the drug in nanoparticles or water-soluble cyclodextrin / drug complexes. Specifically, the microsuspension may comprise approximately 80% to approximately 95% of the drug in microparticles having a diameter of approximately 1 µm to approximately 10 µm, and approximately 5% to approximately 20% of the drug in nanoparticles or water-soluble cyclodextrin / active pharmaceutical ingredient complexes. According to a preferred embodiment, the aqueous composition comprises drug / cyclodextrin complexes, preferably corticosteroid / cyclodextrin complexes, and more preferably dexamethasone / γ-cyclodextrin complexes. Document WO2018 / 100434, which is incorporated herein by reference, describes examples of compositions comprising drug / cyclodextrin complexes. Additive to prevent drug oxidation The aqueous composition includes an additive to prevent drug oxidation. The applicants surprisingly found that the addition of this additive stabilizes the pH of the aqueous composition and prevents a pH drop. In a preferred embodiment, the additive to prevent drug oxidation is selected from antioxidants, oxygen scavengers, and mixtures thereof. Antioxidants typically include phenolic antioxidants and reducing agents. Phenolic antioxidants are sterically hindered phenols that react with free radicals, blocking the oxidation reaction. Examples of phenolic antioxidants include butylhydroxyanisole (BHA), butylhydroxytoluene (BHT), tert-butylhydroquinone (TBHQ), and 3,4-d-hydroxybenzoic acid, dodecyl 3,4,5-trihydroxybenzoate (lauryl gallate). Reducing agents are compounds with a lower redox potential than the substance they are intended to prevent oxidation from. Reducing agents remove oxygen from the medium and thus delay or prevent oxidation. Examples of reducing agents include sodium thiosulfate (STS) and other industrial food preservatives with antioxidant properties.Examples of antioxidants also include naturally occurring water-soluble antioxidants such as ascorbic acid, malic acid, citric acid, tartaric acid, lactic acid, and other organic acids and their derivatives. Additional antioxidants may also be selected from known food antioxidants. In one specific modality, the additive to prevent oxidation of the drug is sodium thiosulfate. In another specific modality, the additive to prevent oxidation of the drug is selected from sodium thiosulfate, methionine, 3,4-dihydroxybenzoic acid, sodium citrate, malic acid, sodium ascorbate, tartaric acid, α-monothioglycerol, butylated hydroxyanisole, lauryl gallate, lactic acid, tert-butylhydroquinone and their salts or derivatives, or mixtures thereof.More preferably, said additive is selected from sodium thiosulfate, methionine (typically L-methionine), 3,4-dihydroxybenzoic acid, sodium citrate (e.g., sodium citrate, tribasic dehydrate), malic acid (typically DL-malic acid), sodium ascorbate (e.g., (+)-L-sodium ascorbate), tartaric acid (typically DL-tartaric acid), α-monothioglycerol, and butylated hydroxyanisole, and even more preferably, said additive is selected from sodium thiosulfate, methionine, and 3,4-dihydroxybenzoic acid. Of course, a mixture of said antioxidants may be added as an additive to prevent oxidation of the drug. The additive to prevent drug oxidation, typically sodium thiosulfate, methionine, or 3,4-dihydroxybenzoic acid, may be added at a concentration of at least 0.05% (w / v), preferably at a concentration between 0.05% (w / v) and 1% (w / v), more preferably between 0.1% and 0.5%, and even more preferably between 0.2% (w / v) and 0.4% (w / v). The additive to prevent drug oxidation, typically sodium thiosulfate, may be added at a concentration between 0.2% (w / v) and 0.3% (w / v). As used in this document, the 0.3% (w / v) sodium thiosulfate concentration refers to anhydrous sodium thiosulfate. This corresponds to 0.471 g / 100 mL of sodium thiosulfate pentahydrate. For other antioxidants, the molar equivalent of 0.3% sodium thiosulfate in the aqueous composition can typically be used. pH of the composition Advantageously, the pH of the aqueous composition comprising a drug is between 4 and 9, preferably between 5 and 8. Typically, the pH of the aqueous composition comprising a drug is physiological pH. Advantageously, the pH of the aqueous composition comprising a corticosteroid is between 4 and 8, preferably between 4.5 and 6. In one specific modality, the pH of the aqueous composition is stabilized between 4 and 8, preferably between 4.5 and 6, for more than 6 months, preferably more than 9 months, when stored at 25°C, 40% relative humidity, according to ICH guidelines. Aqueous composition MA / a / ZUZl / UlD / O / Advantageously, the aqueous composition is an ophthally acceptable medium. The term ophthally acceptable medium is intended to mean a medium suitable for ophthalmic administration of the composition. The ophthally acceptable medium is preferably a liquid. The aqueous composition may include an organic solvent. In this case, the aqueous composition preferably does not include an organic solvent. In one particular embodiment, the ophthally acceptable medium comprises no solvent other than water. The ophthally acceptable medium may thus correspond to an aqueous eye drop vehicle. In one specific embodiment, the aqueous composition is an unbuffered aqueous eye drop vehicle. According to a specific embodiment, the aqueous composition comprises water and optionally an additive selected from the group consisting of a preservative, a stabilizing agent, an electrolyte, and combinations thereof. In particular, the ophthally acceptable medium may comprise a preservative. A preservative may be used to limit bacterial growth in the composition. Examples of preservatives include benzalkonium chloride, chlorobutanol, thimerosal, phenylmercuric acetate, phenylmercuric nitrate, methylparaben, phenylethyl alcohol, and combinations thereof. The amount of preservative in the composition described may be from 0 to 1%, particularly from 0.001 to 0.5%, more particularly from 0.005 to 0.1%, and even more particularly from 0.01 to 0.04%, by weight of preservative based on the volume of the composition. In a preferred embodiment, the aqueous composition is preservative-free. In particular, the aqueous composition may include a stabilizing agent. An example of a suitable stabilizing agent is disodium edetate. The amount of stabilizing agent in the composition described may be from 0 to 1%, specifically from 0.01 to 0.5%, and more specifically from 0.08 to 0.2% by weight of stabilizing agent based on the volume of the composition. In particular, the ophthally acceptable medium may comprise an electrolyte. An electrolyte may be used specifically to make the composition isotonic. Examples of suitable electrolytes include sodium chloride, potassium chloride, and combinations thereof. Preferably, the electrolyte is sodium chloride. The amount of electrolyte in the composition described may be from 0 to 2%, particularly from 0.1 to 1.5%, and more particularly from 0.2 to 1% by weight of electrolyte based on the volume of the composition. The aqueous composition may also include a polymer. In particular, this polymer may be a water-soluble polymer. Furthermore, this polymer may be a viscosity-enhancing polymer. The term viscosity-enhancing polymer means a polymer that increases the viscosity of a liquid. The polymer increases the viscosity of the composition. The increased viscosity results in improved physical stability of the composition. As such, the composition is less prone to solid complex sedimentation when it includes a polymer. Therefore, the polymer can be considered a polymeric stabilizing agent. In particular, the polymer may be a surface-active polymer. The term surface-active polymer is intended to mean a polymer that exhibits surfactant properties.Surface-active polymers can, for example, comprise hydrophobic chains grafted onto a polymer with a hydrophilic backbone; hydrophilic chains grafted onto a hydrophobic backbone; or alternating hydrophilic and hydrophobic segments. The first two types are called graft copolymers, and the third type is called a block copolymer. In one embodiment, the ophthalmic composition of the description comprises a polymer selected from the group consisting of a polyoxyethylene fatty acid ester; a polyoxyethylene alkylphenyl ether; a polyoxyethylene alkyl ether; a cellulose derivative such as alkylcellulose, hydroxyalkylcellulose and hydroxyalkyl alkylcellulose; a carboxyvinyl polymer such as a carbomer, for example Carbopol 971 and Carbopol 974; a polyvinyl polymer; a polyvinyl alcohol; a polyvinylpyrrolidone; a polyoxypropylene and polyoxyethylene copolymer; tyloxapol; and combinations thereof. Examples of suitable polymers include, but are not limited to, polyethylene glycol monostearate, polyethylene glycol distearate, hydroxypropyl methylcellulose, hydroxypropylcellulose, polyvinylpyrrolidone, polyoxyethylene lauryl ether, polyoxyethylene octyldodecyl ether, polyoxyethylene stearyl ether, polyoxyethylene myristyl ether, polyoxyethylene oleyl ether, sorbitan esters, polyoxyethylene hexadecyl ether (e.g., cetomacrogol 1000), polyoxyethylene castor oil derivatives, polyoxyethylene sorbitan fatty acid esters (e.g., Tween 20 and Tween 80 (ICI Specialty Chemicals)); polyethylene glycols (e.g., Carbowax 3550 and 934 (Union Carbide)), polyoxyethylene stearates, calcium carboxymethylcellulose, sodium carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxypropyl methylcellulose, cellulose, polyvinyl alcohol (PVA), poloxamers (e.g., Pluronics F68 and FI08, which are block copolymers of ethylene oxide and propylene oxide);poloxamines (for example, Tetronic 908, also known as Poloxamine 908, which is a tetrafunctional block copolymer derived from the sequential addition of propylene oxide and ethylene oxide to ethylenediamine (BASF Wyandotte Corporation, Parsippany, NJ)); Tetronic 1508 (T-1508) (BASF Wyandotte Corporation), Tritons X-200, which is an alkyl aryl polyethersulfonate (Rohm and Haas); PEG-derived phospholipid, PEG-derived cholesterol, PEG-derived cholesterol derivative, PEG-derived vitamin A, PEG-derived vitamin E, random copolymers of vinylpyrrolidone and vinyl acetate, combinations thereof and the like; Particularly preferred examples of polymers according to the description are tyloxapol and a copolymer of polyoxypropylene and polyoxyethylene. More particularly, the polyoxypropylene and polyoxyethylene copolymer can be a triblock copolymer comprising a hydrophilic block-hydrophobic block-hydrophilic block configuration. In one embodiment, the disclosure composition comprises a polymer that is a poloxamer. The poloxamers may include any type of poloxamer known in the art. The poloxamers include poloxamer 101, poloxamer 105, poloxamer 108, poloxamer 122, poloxamer 123, poloxamer 124, poloxamer 181, poloxamer 182, poloxamer 183, poloxamer 184, and poloxamer 184. 185, poloxamer 188, poloxamer 212, poloxamer 215, poloxamer 217, poloxamer 231, poloxamer 234, poloxamer 235, poloxamer 237, poloxamer 238, poloxamer 282, poloxamer 284, poloxamer 288, poloxamer 331, poloxamer 333, poloxamer 334, poloxamer 335, poloxamer 338, poloxamer 401, poloxámero 402, poloxámero 403, poloxámero 407, benzoato de poloxámero 105 y dibenzoato de poloxámero 182. Los poloxámeros también se conocen por su nombre comercial Pluronic tal como Pluronic 10R5, Pluronic 17R2, Pluronic 17R4, Pluronic 25R2, Pluronic 25R4, Pluronic 31 Rl, Pluronic F 108, Pluronic F 108, Pluronic F 108, Pluronic F 108NF, Pluronic F 127, Pluronic F 127 NF, Pluronic F 127, Pluronic F 127, Pluronic F 38, Pluronic F 38, Pluronic F 68, Pluronic F 77, Pluronic F 87, Pluronic F 88, Pluronic F 98, Pluronic L 10, Pluronic L 101, Pluronic L 121, Pluronic L 31, Pluronic L 3S, Pluronic L 43, Pluronic L 44, Pluronic L 61, Pluronic L 62, Pluronic L 62 LF, Pluronic L 620, Pluronic L 64, Pluronic L 81, Pluronic L 92, Pluronic L 44, Pluronic N 3, Pluronic P 103, Pluronic P 104, Pluronic P 85, Pluronic P 123, Pluronic P 65, Pluronic P 84, Pluronic P 85, combinaciones de los mismos y similares. Polymers that are especially useful as stabilizers are poloxamers. Poloxamers can include any type of poloxamer known to the art. Poloxamers include poloxamer 101, poloxamer 105, poloxamer 108, poloxamer 122, poloxamer 123, poloxamer 124, poloxamer 181, poloxamer 182, poloxamer 183, poloxamer 184, poloxamer 185, poloxamer 188, poloxamer 212, poloxamer 215, poloxamer 217, poloxamer 231, poloxamer 234, poloxamer 23S, poloxamer 237, poloxamer 238, poloxamer 282, poloxamer 284, poloxamer 288, poloxamer 331, poloxamer 333, poloxamer 334, poloxamer 33S, poloxamer 338, poloxamer 401, poloxamer 402, poloxamer 403, poloxamer 407, poloxamer benzoate 105, and poloxamer 182 dibenzoate. Poloxamers are also known by their trade names Pluronic, such as Pluronic 10R5, Pluronic 17R2, Pluronic 17R4, Pluronic 25R2, Pluronic 25R4, Pluronic 31 Rl, Pluronic F 108 Cast Solid Surfacta, Pluronic F 108 NF,Pluronic F 108 Pastille, Pluronic F 108NF Prill Poloxámero 338, Pluronic F 127, Pluronic F 127 NF, Pluronic F 127 NF 500 BHT Prill, Pluronic F 127 NF Prill Poloxámero 407, Pluronic F 38, Pluronic F 38 Pastille, Pluronic F 68, Pluronic F 68 Pastille, Pluronic F 68 LF Pastille, Pluronic F 68 NF, Pluronic F 68 NF Prill Poloxámero 188, Pluronic F 77, Pluronic F 77 Micropastille, Pluronic F 87, Pluronic F 87 NF, Pluronic F 87 NF Prill Poloxámero 237, Pluronic F 88, Pluronic F 88 Pastille, Pluronic F 98, Pluronic L 10, Pluronic L 101, Pluronic L 121, Pluronic L 31, Pluronic L 35, Pluronic L 43, Pluronic L 44 NF Poloxámero 124, Pluronic L 61, Pluronic L 62, Pluronic L 62 LF, Pluronic L 620, Pluronic L 64, Pluronic L 81, Pluronic L 92, Pluronic L44 NF INH surfactant Poloxámero 124, View, Pluronic N 3, Pluronic P 103, Pluronic P 104, Pluronic P 105, Pluronic P 123 surfactant, Pluronic P 65, Pluronic P 84, Pluronic P 85, combinations thereof and similar. In particular, said polymer is poloxamer 407. An additional polymeric stabilizing agent compatible with the compositions and methods described herein is tyloxapol. In preferred embodiments, the stabilizer and cosolubilizer is tyloxapol, which is a polymer of 4-(1,1,3,3-tetramethylbutyl)phenol with formaldehyde and oxirane. This description also relates to a method for stabilizing the pH of an aqueous composition comprising corticosteroid / cyclodextrin complexes, said method comprising the addition of an antioxidant to prevent oxidation of the corticosteroid, for example one or more of the antioxidant as described in the preceding sections, typically sodium thiosulfate. This description also relates to a method for stabilizing the pH of an aqueous composition comprising a drug. This method involves using an oxygen absorber to prevent oxidation of the drug. The aqueous composition comprising the drug can be stored in vials, and the vials can be packaged in sealed bags, typically aluminum pouches, containing an oxygen absorber. Advantageously, the oxygen absorber contains iron particles. Aqueous composition comprising a corticosteroid This description also relates to an aqueous composition comprising a corticosteroid, cyclodextrin, and an additive for preventing oxidation of the corticosteroid, wherein said additive, for example, reducing agents, water-soluble natural antioxidants, or phenolic antioxidants as described in previous sections, typically sodium thiosulfate, is present in the composition at a concentration between 0.15% (w / v) and 0.45% (w / v), and preferably at a concentration between 0.2% (w / v) and 0.4% (w / v). The additive for preventing oxidation of the corticosteroid, for example, reducing agents, water-soluble natural antioxidants, or phenolic antioxidants as described in previous sections, typically sodium thiosulfate, may be present at a concentration between 0.2% (w / v) and 0.3% (w / v). Corticosteroids Corticosteroids include glucocorticoids and mineralocorticoids. Advantageously, the corticosteroid is selected from betamethasone-type corticosteroids, which are glucocorticoids with a Ci6 methyl substitution. Betamethasone-type corticosteroids include alclomethasone, beclomethasone, betamethasone, clobethasone, clocortolone, desoximethasone, dexamethasone, diflucortolone, flumethasone, fluocortolone, fluprednidene, fluticasone, halomethasone, and mometasone. Preferably, the drug is dexamethasone. In one specific formulation, the corticosteroid is prone to oxidation, meaning it can be degraded through an oxidation pathway. In some cases, the degradation products of this oxidation are acidic, and adding an additive to prevent drug oxidation avoids the formation of these acidic degradation products. The concentration of the corticosteroid in the aqueous composition described may be from approximately 0.1 mg / ml to approximately 100 mg / ml, specifically from approximately 1 mg / ml to approximately 100 mg / ml, particularly from approximately 1 mg / ml to approximately 50 mg / ml, more particularly from approximately 1 mg / ml to approximately 40 mg / ml, even more particularly from approximately 5 mg / ml to approximately 35 mg / ml, and still more particularly from approximately 10 mg / ml to approximately 30 mg / ml. The concentration of the corticosteroid in the aqueous composition described may be from approximately 5 mg / ml to approximately 30 mg / ml, specifically from approximately 10 mg / ml to approximately 25 mg / ml. The amount of corticosteroids in the aqueous composition can be from 0.5 to 5%, in particular from 1 to 4%, and more particularly from 1.5 to 3%, by weight of corticosteroids depending on the volume of the composition. Cyclodextrin The aqueous composition comprises cyclodextrin. The amount of cyclodextrin in the aqueous composition may be from 1 to 35%, particularly from 5 to 30%, more particularly from 10 to 27%, and even more particularly from 12 to 25%, by weight of cyclodextrin relative to the volume of the composition. In certain formulations containing dexamethasone, the amount of cyclodextrin, typically gamma-cyclodextrin, in the aqueous composition is 10 to 25%, and the amount of dexamethasone is 1.5%. In other formulations, the amount of cyclodextrin, typically gamma-cyclodextrin in the aqueous composition, may be 20 to 25%, for example 23%, particularly in combination with an amount of between 2.0 and 3.5% dexamethasone, preferably with approximately 3% dexamethasone. The corticosteroid can form a corticosteroid / cyclodextrin complex as described above. Additive to prevent corticosteroid oxidation The aqueous composition includes an additive to prevent oxidation of the corticosteroid. The applicants surprisingly found that the addition of an oxidation-prevention additive stabilizes the pH of the aqueous composition and prevents a pH drop. In a preferred embodiment, the additive to prevent corticosteroid oxidation is selected from antioxidants, oxygen scavengers, and mixtures thereof. Antioxidants include phenolic antioxidants and reducing agents, such as water-soluble natural antioxidants or other known food antioxidants. Phenolic antioxidants include butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butylhydroquinone (TBHQ), and 3,4-d-hydroxybenzoic acid, dodecyl 3,4,5-trihydroxybenzoate (lauryl gallate). Reducing agents are compounds with a lower redox potential than the drug they are intended to prevent from oxidation. Reducing agents remove oxygen from the medium and thus delay or prevent oxidation. Sodium thiosulfate (STS) is one example of a reducing agent. Other examples of antioxidants include water-soluble natural antioxidants such as ascorbic acid, malic acid, citric acid, tartaric acid, lactic acid, and other organic acids and their derivatives. Other antioxidants can be selected from among known cosmetic or food antioxidants. In one specific modality, the additive to prevent oxidation of the drug is sodium thiosulfate. In another specific modality, the additive to prevent oxidation of the drug is selected from sodium thiosulfate, methionine, 3,4-dihydroxybenzoic acid, sodium citrate, malic acid, sodium ascorbate, tartaric acid, α-monothioglycerol, butylated hydroxyanisole, lauryl gallate, lactic acid, tert-butylhydroquinone and their salts or derivatives.More preferably, said additive is selected from sodium thiosulfate, methionine (typically L-methionine), 3,4-dihydroxybenzoic acid, sodium citrate (e.g., sodium citrate, tribasic dehydrate), malic acid (typically DL-malic acid), sodium ascorbate (e.g., (+)-L-sodium ascorbate), tartaric acid (typically DL-tartaric acid), α-monothioglycerol, and butylated hydroxyanisole, and even more preferably, said additive is selected from sodium thiosulfate, methionine, and 3,4-dihydroxybenzoic acid. Of course, a mixture of said antioxidants may be added as an additive to prevent oxidation of the drug. pH of the composition Advantageously, the pH of the aqueous composition comprising a corticosteroid is between 4 and 8, preferably between 4.5 and 6. In one specific modality, the pH of the aqueous composition is stabilized between 4 and 8, preferably between 4.5 and 6, for more than 6 months, preferably more than 9 months, when stored at 25°C, 40% relative humidity, according to ICH guidelines. Aqueous composition Advantageously, the aqueous composition is an ophthally acceptable medium, as described above. In a particularly preferred embodiment, the aqueous composition comprises: 4% dexamethasone, for example 1.5% to 3% dexamethasone; 35% γ-cyclodextrin, for example 5 to 25% y-cyclodextrin; 2.2 to 2.8% polymer, or 2.8 to 3.2%, for example 2.5% or 3.0% polymer, typically poloxamer; to 0.2% stabilizing agent, for example 0.1% stabilizing agent, typically disodium edetate; 0.15 to 0.45% of an additive to prevent oxidation of the corticosteroid, for example between 0.2% and 0.4%, or between 0.2% and 0.3%, of an additive to prevent oxidation of the corticosteroid, typically phenolic antioxidants or reducing agents, such as water-soluble natural antioxidants, and most preferably sodium thiosulfate, L-methionine or 3,4-dihydroxybenzoic acid; to 1% electrolyte, for example 0.57% electrolyte, typically sodium chloride; and water; where the % are % by weight based on the volume of the composition. The aqueous composition comprising a corticosteroid, cyclodextrin, and an additive to prevent oxidation of the corticosteroid can be stored in plastic vials, typically LDPE vials, or glass vials. Preferred aqueous composition with dexamethasone In one particular embodiment, an aqueous composition comprises or consists essentially of; 4% dexamethasone, for example 1.5% to 3% dexamethasone; 35% γ-cyclodextrin, for example 5 to 25% y-cyclodextrin; to 0.2% stabilizing agent, for example 0.1% stabilizing agent, typically disodium edetate; to 1% electrolyte, for example 0.57% electrolyte, typically sodium chloride; and water; where the % are % by weight based on the volume of the composition. In one particular embodiment, an aqueous composition for use as described herein comprises or consists essentially of; 4% dexamethasone, for example 1.5% to 3% dexamethasone; 35% γ-cyclodextrin, for example 5 to 25% y-cyclodextrin; optionally 2.2 to 2.8% polymer or 2.8% to 3.2% polymer, for example 2.5% or 3.0% polymer, typically poloxamer; to 0.2% stabilizing agent, for example 0.1% stabilizing agent, typically disodium edetate; 0% to 0.8% of an additive to prevent oxidation of dexamethasone, for example between 0.1% and 0.5%, or between 0.2% and 0.4%, of an additive to prevent oxidation of the corticosteroid, typically phenolic antioxidants or reducing agents, such as water-soluble natural antioxidants, and most preferably sodium thiosulfate, L-methionine or 3,4-dihydroxybenzoic acid; to 1% electrolyte, for example 0.57% electrolyte, typically sodium chloride; and water; where the % are % by weight based on the volume of the composition. More specifically, a particularly preferred modality is an eye drop formulation comprising or consisting essentially of: 1.5% dexamethasone; 14% γ-cyclodextrin; 2.5% poloxamer; to 0.2% of stabilizing agent, for example 0.1% of disodium edetate; to 1% electrolyte, for example 0.57% sodium chloride; 0% to 0.6% of an additive to prevent oxidation of dexamethasone, for example between 0.2% and 0.4% of an additive to prevent oxidation of the corticosteroid, typically phenolic antioxidants or reducing agents, such as water-soluble natural antioxidants, and most preferably sodium thiosulfate, L-methionine or 3,4-dihydroxybenzoic acid; and water; where the % are % by weight based on the volume of the composition. Typically, an eye drop formulation has the following components: 1.5% dexamethasone; - 14% γ-cyclodextrin; 2.5% poloxamer; 0.1% disodium edetate; 0.57% sodium chloride; and between 0.2% and 0.4% sodium thiosulfate; water; Another particular modality is an eye drop formulation that essentially comprises or consists of: 3% dexamethasone; 35% γ-cyclodextrin, for example 20 to 25% γ-cyclodextrin; optionally 2.8 to 3.2% polymer, for example 3.0% polymer, typically poloxamer; to 0.2% stabilizing agent, for example 0.1% stabilizing agent, typically disodium edetate; 0% to 0.6% of an additive to prevent oxidation of dexamethasone, for example between 0.1% and 0.5%, or between 0.2% and 0.4%, of an additive to prevent oxidation of the corticosteroid, typically phenolic antioxidants or reducing agents, such as water-soluble natural antioxidants, and most preferably sodium thiosulfate, L-methionine or 3,4-dihydroxybenzoic acid; to 1% electrolyte, for example 0.57% electrolyte, typically sodium chloride; and water; where the % are % by weight based on the volume of the composition. Another particular modality is an eye drop formulation that essentially comprises or consists of: 3% dexamethasone; between 20 and 25% of γ-cyclodextrin; optionally between 2.8 and 3.2% poloxamer; for example 3.0% poloxamer; to 0.2% of stabilizing agent, for example 0.1% of disodium edetate; to 1% electrolyte, for example 0.57% sodium chloride; 0% to 0.6% of an additive to prevent oxidation of dexamethasone, for example between 0.1% and 0.5%, or between 0.2% and 0.4%, of an additive to prevent oxidation of the corticosteroid, typically phenolic antioxidants or reducing agents, such as water-soluble natural antioxidants, and most preferably sodium thiosulfate, L-methionine or 3,4-dihydroxybenzoic acid; and water; where the % are % by weight based on the volume of the composition. Typically, an eye drop formulation has the following components: 3% dexamethasone; between 20 and 25% of γ-cyclodextrin; for example 23% of y-cyclodextrin; between 2.8 and 3.2% poloxamer; 0.1% disodium edetate; 0.57% sodium chloride; and between 0.2% and 0.4% sodium thiosulfate; typically 0.3% sodium thiosulfate, water; All the aqueous formulations or compositions described above are advantageously free of preservatives. The final formulation for use as eye drops is a microsuspension that includes complex aggregates of dexamethasone and β-cyclodextrin. Typically, 60 to 95% by weight, more particularly 70 to 90% by weight, of the dexamethasone in the composition may be in the form of solid dexamethasone and β-cyclodextrin complexes. The methods for preparing such formulations comprise the following steps: a) Mix the dexamethasone in an ophthally acceptable medium with the other excipients and heat until the dexamethasone is substantially dissolved in the ophthally acceptable medium; for example, at least 60 minutes at a temperature between 80°C and 110°C, b) suspend the gamma cyclodextrin in an ophthally acceptable medium to form a suspension and heat said suspension until the cyclodextrin is substantially dissolved in the ophthally acceptable medium; c) mix the compositions from step a) and b) at a temperature TI below 120°C and heat the mixture to a temperature TI below 120°C for a time t; and d) cooling the resulting solution to a temperature T2 to obtain an aqueous composition comprising a solid complex of dexamethasone and a cyclodextrin (preferably gamma cyclodextrin). In the above manufacturing method, dexamethasone may be suspended in an ophthally acceptable cyclodextrin-free medium, optionally with the other excipients. The resulting suspension may have a milky appearance. Separately, gamma-cyclodextrin may be suspended in an ophthally acceptable active pharmaceutical ingredient-free medium. The resulting suspension may also have a milky appearance. The two suspensions may be heated or sterilized, for example, by heating in an autoclave at 121°C for 20 minutes. The two heated suspensions or solutions may then be mixed together, and the mixture may be heated until the dexamethasone-gamma-cyclodextrin complex is formed. The resulting solution may be cooled at a rate sufficient to produce a microsuspension comprising a solid gamma-cyclodextrin / active pharmaceutical ingredient complex. Detailed methods for manufacturing microsuspensions are also described in document WO2018100434. Such a microsuspension as described above is stable and can be used as an eye drop formulation. In specific formulations, these aqueous compositions with 1.5% (w / v) are preservative-free ophthalmic microsuspensions. They can be presented in unit doses of 0.5 ml fill volume, for example, in LDPE plastic material. The resulting suspension can be stored at room temperature, below 25°C, for at least 2, 3, 6, 12, 18, or 24 months. Use of an aqueous composition comprising a corticosteroid The aqueous compositions described herein may be used to treat eye conditions, particularly anterior or posterior ocular conditions, and more specifically uveitis, macular edema, macular degeneration, retinal detachment, ocular tumors, fungal or viral infections, multifocal choroiditis, diabetic retinopathy, proliferative vitreoretinopathy (PVR), sympathetic ophthalmia, Vogt-Koyanagi-Harada (VKH) syndrome, histoplasmosis, uveal diffusion, and vascular occlusion. The aqueous compositions described herein may be particularly useful in the treatment of uveitis, macular edema, diabetic retinopathy, proliferative vitreoretinopathy (PVR), and vascular occlusions. Aqueous compositions comprising dexamethasone as described can be used in particular for the treatment of macular edema. In this case, the aqueous compositions comprising dexamethasone as described can be administered topically to the eye in an amount of 1 drop of the composition three times a day. The amount of dexamethasone in said composition can be from 1 to 5%, in particular from 1.5% to 3% by weight of dexamethasone depending on the volume of the composition. The compositions described, which contain dexamethasone, do not need to be administered as frequently as known topical dexamethasone compositions, i.e., one drop of the composition six times a day. In fact, due to the viscosity of the composition, the solid complexes of the disclosed composition exhibit a longer contact time on the surface of the eye compared to known compositions, thus increasing the bioavailability of the drug. This description also covers the use of the aqueous composition described herein as an eye drop solution. In one embodiment, aqueous compositions comprising dexamethasone according to the description can be used in particular for the treatment of central retinal vein occlusion or eye inflammations such as inflammation after cataract surgery, glaucoma, anterior chamber inflammation, central macular edema. This description also refers to the use of the aqueous composition described herein for the manufacture of a medicament for the treatment of an eye condition, particularly an anterior or posterior eye condition. The aqueous compositions described herein may be particularly useful in the manufacture of a medicament for the treatment of central retinal vein occlusion or eye inflammations such as inflammation following cataract surgery, glaucoma, anterior chamber inflammation, or central macular edema. The description also refers to a method for treating an eye condition, in particular an anterior eye condition or a posterior eye condition, the method comprising administering to a subject in need, preferably a human being, a therapeutically efficient amount of the aqueous composition of the description. As used herein, the term "treat" includes reversing, alleviating, inhibiting the progression of, preventing, or reducing the likelihood of the disease, disorder, or condition to which the term applies, or one or more symptoms or manifestations of that disease, disorder, or condition. "Prevention" refers to causing a disease, disorder, condition, or symptom or manifestation thereof, or worsening of its severity, not to occur. Accordingly, the compounds described herein may be administered prophylactically to prevent or reduce the incidence or recurrence of the disease, disorder, or condition. As used herein, the term therapeutically effective amount refers to an amount of drug that will elicit a biological or medical response from a subject, e.g., improve symptoms, relieve conditions, slow or delay disease progression, or prevent disease. Preferred use of dexamethasone eye drop formulations Aqueous compositions and eye drop formulations containing dexamethasone, as described above, are preferably used in the treatment or prevention of diabetic macular edema; inflammation after eye surgery, typically after cataract surgery; Cystoid macular edema following eye surgery; Acute anterior uveitis; Dry eye disease and blepharitis; Other acute or chronic inflammatory eye disorders, such as graft-versus-host disease (GVHD), vernal conjunctivitis, pterygium, chalazion, or allergic conjunctivitis; - Post-corneal transplantation to control inflammation and prevent rejection; or, Treatment of non-infectious uveitis affecting the posterior segment of the eye. The specific modalities of such use are described in more detail in the following section. Methods for treating diabetic macular edema. The eye drop formulations described herein have been tested in clinical trials in patients suffering from such disorders, and the results are provided in the Examples. In particular, the 1.5% (w / v) dexamethasone eye drop formulation has been shown to be effective in treating diabetic macular edema. More specifically, a method for treating diabetic macular edema in a subject in need is provided herein, said method comprising topically administering to an affected eye of said subject, a therapeutically efficient amount of an eye drop formulation comprising 1.5% (w / v) dexamethasone (typically one of the preferred formulations as described above), preferably with a dosage of one, two, three, four, five or six drops daily, for example, for a duration of at least 6, 7, 8, 9, 10, 11 or 12 weeks. In a preferred embodiment of the method, the eye drop formulation for use in the above method comprises or essentially consists of: 1.5% dexamethasone; 14% γ-cyclodextrin; 2.5% poloxamer; to 0.2% of stabilizing agent, for example 0.1% of disodium edetate; to 1% electrolyte, for example 0.57% sodium chloride; 0% to 0.6% of an additive to prevent oxidation of dexamethasone, for example between 0.1% and 0.5%, or between 0.2% and 0.4%, of an additive to prevent oxidation of the corticosteroid, typically sodium thiosulfate; and water; where the % are % by weight based on the volume of the composition. In a preferred embodiment of the method, the eye drop formulation for use in the above method comprises or essentially consists of: 3% dexamethasone; between 20% and 25% of γ-cyclodextrin; for example, 23% of γ-cyclodextrin; 2.5% poloxamer; to 0.2% of stabilizing agent, for example 0.1% of disodium edetate; to 1% electrolyte, for example 0.57% sodium chloride; 0% to 0.6% of an additive to prevent oxidation of dexamethasone, for example between 0.1% and 0.5%, or between 0.2% and 0.4%, of an additive to prevent oxidation of the corticosteroid, typically sodium thiosulfate; and water; where the % are % by weight based on the volume of the composition. Typically, central macular thickness (CMT), as assessed by SD-OCT, can be significantly reduced after 12 weeks of such treatment in a patient suffering from AMD, for example, by more than 10% of CMT measured from baseline, with CMT determined as described in the examples below. Furthermore, pinhole visual acuity can improve from baseline to at least 3 ETDRS letters after 12 weeks of the above treatment in patients with AMD. Pinhole visual acuity can be determined as described in the examples below. iviA / a / zuzi / uio / or This treatment is particularly useful for patients who do not respond or respond inadequately to VEGF inhibitor treatments (patients not previously treated with VEGFi) and / or who are not candidates for invasive treatments for diabetic macular edema. Therefore, in a particular modality of the above method for treating diabetic macular edema, the patient is selected from patients not previously treated with VEGFi, with retinal fat accumulation in the affected eye due to diabetic macular edema. Typically, the patient is a human patient, and more specifically an adult human patient. Methods for treating inflammation after eye surgery It has also been shown to be effective in treating inflammation and / or pain after eye surgery, particularly after cataract surgery (postoperative cataract) with a 1.5% (w / v) dexamethasone eye drop formulation. Therefore, a method is provided here for treating inflammation following eye surgery, particularly following cataract surgery (postoperative cataract) in a subject in need, said method comprising topically administering to an affected eye of said subject, a therapeutically efficient amount of an eye drop formulation comprising 1.5% (w / v) or 3% (w / v) dexamethasone (typically a preferred formulation as described above), preferably with a dose of one or two drops daily, for example for a period of at least 16 weeks. In a preferred embodiment of the method, the eye drop formulation for use in the above method comprises or essentially consists of: 1.5% dexamethasone; 14% γ-cyclodextrin; 2.5% poloxamer; to 0.2% of stabilizing agent, for example 0.1% of disodium edetate; to 1% electrolyte, for example 0.57% sodium chloride; 0% to 0.6% of an additive to prevent oxidation of dexamethasone, for example between 0.1% and 0.5%, or between 0.2% and 0.4%, of an additive to prevent oxidation of the corticosteroid, typically sodium thiosulfate; And water; where the % are % by weight based on the volume of the composition. Generally, eye pain and inflammation can be significantly reduced or eliminated after 15 days of the above treatment in a patient experiencing pain and inflammation following eye surgery, for example, cataract surgery. Pain can be determined by a numerical pain rating, as described in the examples below. Inflammation can be determined by cell counts of the anterior chamber cells, as described in the examples below. Typically, the patient is a human patient, and more specifically an adult human patient. Use of an additive to prevent the oxidation of a corticosteroid This description also refers to the use of an additive to prevent the oxidation of a corticosteroid to stabilize the pH of an aqueous composition comprising a corticosteroid. EXAMPLES Example 1: Formulation of aqueous dexamethasone eye drops Aqueous dexamethasone eye drops were prepared that had a composition according to Table 1. iviA / a / zuzi / uio / o / Table 1: Composition of dexamethasone aqueous eye drops Ingredients Quantity (% w / v) Dexamethasone 1.50 γ-Cyclodextrin 14.00 Disodium edetate 0.10 Poloxamer 407 2.50 Sodium chloride 0.57 Water for injection qs 100.00 The eye drops were prepared as follows: Part A: Disodium edetate, Poloxamer 407 and sodium chloride were dissolved in pure water at 80°C. Dexamethasone was added to the excipient mixture just before sterilization. Part B: γ-cyclodextrin was suspended separately in pure water at 80°C. Part A and Part B were sterilized at 121°C for 15 minutes. After sterilization, Part B was added to Part A at 95°C. After stirring for 15 minutes, the solution was rapidly cooled to room temperature (for 20 minutes) to form a cloudy suspension. The suspension was filled and sealed in glass vials or low-density polyethylene (LDPE) vials. The pH of the eye drops was measured in glass vials and in LDPE vials during storage at 25°C. The results are shown in Table 2. iviA / a / ¿u¿ ι / υ io / o / Table 2: pH of the eye drops during storage. NT means not tested. Vial pH at a given time (months) during storage at 25°C 0 1 3 6 9 12 18 22 LDPE Vial 4.5 NT 4.1 3.8 3.7 3.7 3.6 3.5 Glass Vial NT NT NT 4.36 NT 4.34 NT NT These results show that when eye drops are stored in LDPE vials, the pH drops over time, whereas in the glass vial, the pH remains stable. Example 2: Dexamethasone aqueous eye drop formulation containing sodium thiosulfate (ISTS) Eye drops were prepared with different percentages of sodium thiosulfate. The composition of the eye drops is shown in Table 3. Sodium thiosulfate was added: - to the formulation of aqueous eye drops according to Table 1 (Example 2A), or - during the preparation of the aqueous formulation of eye drops (example 2B). In this case, the eye drops were prepared according to the protocol described in example 1 and sodium thiosulfate was added in part A, along with disodium edetate, Poloxamer 407 and sodium chloride (Table 3). Table 3 Composition of aqueous dexamethasone eye drops containing STS Ingredients Quantity (% w / v) Dexamethasone 1.50 γ-Cyclodextrin 14.00 Sodium thiosulfate 0.05 to 0.6 Disodium edetate 0.10 Poloxamer 407 2.50 Sodium chloride 0.57 Water for injection qs up to 100.00 Eye drops were also prepared with 0.3% sodium thiosulfate (corresponding to 0.471 g of sodium thiosulfate pentahydrate) and different percentages of dexamethasone and γ-cyclodextrin. The compositions of the eye drops are shown in Tables 4 and 5. Sodium thiosulfate was added during the preparation of the aqueous formulation of the eye drops: the eye drops were prepared according to the protocol described in Example 1, and sodium thiosulfate was added in Part A, along with disodium edetate, Poloxamer 407, and sodium chloride. Table 4: Aqueous composition of dexamethasone 2.5% fp / v eye drops Ingredients Quantity (% w / v) Dexamethasone 2.50 γ-Cyclodextrin 22.00 Sodium thiosulfate 0.30 Disodium edetate 0.10 Poloxamer 407 2.50 Sodium chloride 0.57 Water for injection qs 100.00 Table 5 Aqueous composition of dexamethasone 3.0% fp / v eye drops Ingredients Quantity (% w / v) Dexamethasone 3.00 γ-Cyclodextrin 25.00 Sodium thiosulfate 0.30 Disodium edetate 0.10 Poloxamer 407 3.0 Sodium chloride 0.57 Water for injection qs 100.00 Example 3: 5 Stability study of aqueous dexamethasone eye drops containing STS 1. Oxygen and heat stress test The pH of the eye drop formulations containing STS was measured after oxygen and heat stress testing. The eye drops from Examples 2A and 2B were transferred to ten 10 mL glass vials, where they were either purged with nitrogen or oxygen, or stored under atmospheric pressure. All vials were placed in an autoclave and run for 0 to 4 heating cycles (each heating cycle: 121°C for 20 min). The pH was measured for all vials after each cycle; the results are presented in Tables 6 (Example 2A) and 7 (Example 2B). Table 6: pH of eye drop formulations with various concentrations of sodium thiosulfate (example 2A) after 0 to 5 autoclave cycles pH of eye drop formulations containing STS Autoclave cycles 0.05% STS 0.1% STS atmosphere purged with Ch atmosphere purged with Ch 0 4.79 ± 0.00 4.79 ± 0.00 4.79 ± 0.02 4.79 ± 0.02 1 5.15 ± 0.07 4.91 ± 0.03 5.38 ± 0.03 5.52 ± 0.02 2 5.02 ± 0.05 Xa 5.32 ± 0.02 5.15 ± 0.02 3 4.80 ± 0.00 3.92 ± 0.08 5.28 ± 0.03 4.83 ± 0.07 4 4.70 ± 0.00 3.78 ± 0.04 5.18 ± 0.03 4.52 ± 0.08 5 3.65 ± 0.06b aThese samples were not removed from the autoclave by mistake. bSince the samples were not removed from the autoclave after 2 cycles, they were subjected to an additional cycle. Table 7. pH of eye drop formulations with various concentrations of sodium thiosulfate (example 2B) after 0 to 5 autoclave cycles. Samples were purged with oxygen before autoclaving. pH of eye drop formulations with and without STS Autoclave cycles 0% STS - 0.1%(w / v) STS - 0.2%(w / v) STS - 0.3%(w / v) STS 0 4.78 ± 0.02 5.11 ± 0.01 5.17 5.26 ± 0.01 1 3.83 ± 0.05 5.82 ± 0.12 5.91 ± 0.02 5.79 ± 0.02 2 3.46 ± 0.03 5.16 ± 0.37 5.83 ± 0.02 5.77 ± 0.06 3 3.29 ± 0.03 4.66 ± 0.65 5.68 ± 0.02 5.54 ± 0.09 4 3.23 ± 0.02 3.75 ± 0.06 5.43 ± 0.02 5.49 ± 0.09 5 — 3.39 ± 0.03 5.21 ± 0.03 5.25 ± 0.04 These results show that the addition of an antioxidant, STS, prevents the pH of the eye drop formulation from dropping. The eye drop formulations are therefore more stable. 2. pH measurement over 12 months The pH of eye drop formulations containing 0.3% STS (example 2B), filled into LDPE vials and placed in sealed aluminum bags containing air or oxygen, was also measured for 12 months at controlled temperature and humidity according to ICH guidelines (25°C / 40% RH and 40°C / NMT25% RH). The results are presented in Table 8. Table 8. pH of the eye drop formulation containing 0.3% STS. pH of the eye drop formulation with 0.3% STS - in LDPE Lot: OC118B— 180410-2 T0 T / l week T 1 month T 3 months T 6 months T 9 months 25°C / 40%RH 5.24 Air NT 5.19 5.28 5.14 5.27 Oxygen NT 5.21 5.27 5.18 5.27 40°C / 25%RH Air 5.27 5.26 5.29 5.18 NT Oxygen 5.23 5.31 5.22 5.05 NT These studies show that the addition of an antioxidant, STS, prevents a drop in the pH of the eye drop formulation. The eye drop formulations are therefore stable for at least 6 months. Example 4: Aqueous dexamethasone eye drop formulation containing phenolic antioxidants 0.02% butylated hydroxyanisole (BHA) or butylated hydroxytoluene (BHT) was added to the aqueous eye drop formulation according to Table 1. 0.005 g of BHA was dissolved in 10 ml of ethanol before addition to the formulation to achieve a concentration of 0.02% (w / v). 0.005 g of BHT was dissolved in 50 ml of ethanol before addition to the formulation to achieve a concentration of 0.02% (w / v). The eye drops were transferred to 10 ml glass vials, where they were either purged with nitrogen or oxygen, or stored under atmospheric pressure. All vials were placed in an autoclave and run for 0 to 3 heating cycles (each heating cycle: 121°C for 20 min). The pH was measured for all vials after each cycle; the results are presented in Table 9. Table 9 pH of eye drop formulations with 0.02% BHA or BHT after 0 to 3 autoclave cycles pH of eye drop formulations with and without phenolic oxidant Autoclave cycles 0% 0.02% BHA 0.02% BHT 0 4.78 ± 0.02 4.87 4.87 1 3.83 ± 0.05 4.77 ± 0.08 4.74 ± 0.04 2 3.46 ± 0.03 4.49 ± 0.05 4.43 ± 0.03 3 3.29 ± 0.03 4.35 ± 0.06 4.20 ± 0.04 These results show that the addition of a phenolic antioxidant prevents the pH of the eye drop formulation from dropping. The eye drop formulations are therefore more stable. Example 5: Clinical studies using the eye drop formulations described herein (containing 1.5% w / v dexamethasone) ABBREVIATIONS • AC: anterior chamber • AE: adverse events • ANCOVA: analysis of covariance • BCVA: best corrected visual acuity • BID: twice a day (from the Latin bis in die) • CMT: central macular thickness • ETDRS: early treatment study of diabetic retinopathy • HbA1c: hemoglobin A1c • IOP: intraocular pressure • LogMAR: logarithm of the minimum angle of resolution • QD: once a day (from the Latin quaque die) • SD-OCT: spectral-domain optical coherence tomography • TEAEs: treatment of emerging adverse events • USP: United States Pharmacopeia Rating and measurement scales and methods • Proteins in aqueous humor (Fiare) and anterior chamber cells The anterior chamber cell count is recorded as the actual number of cells observed if < 10 cells are observed (only white blood cells should be counted; red blood cells and pigment cells should not be counted). (Jabs, DA, RB Nussenblatt, JT Rosenbaum and G. Standardization of Uveitis Nomenclature Working (2005). Standardization of uveitis nomenclature for reporting clinical data. Results of the First International Workshop. Am J Ophthalmol 140(3): 509-516). Table 10: Anterior Chamber Cells Anterior Chamber Proteins Grade Cell Count Grade Protein Count 0 0 0 None 1 1-10 1 Faint 2 11-25 2 Moderate (clear iris and lens details) 3 26-50 3 Market (blurred iris and lens details) 4 >50 4 Intense (fibrin or aqueous plasmoid) Scale based on (Jabs, Nussenblatt et al. 2005). • Eye Pain The patient evaluates eye pain using a numerical pain rating scale rated from 0 to 10 (McCaffery, M. and A. Beebe (1994). Pain: clinical manual for nursing practice. Nurs Stand 9(11): 55). The examiner asks the patient the following question: On a scale of 0 to 10, where 0 is no pain and 10 is the worst possible or unbearable pain, mark the number that best describes the pain or discomfort you are feeling in your operated eye* at this time. Half the scale (around 5) can be used to describe moderate pain. Only whole number scores are allowed. Clinical Study 1: Use of an aqueous pharmaceutical formulation of dexamethasone (1.5% w / v) in the treatment of diabetic macular edema This was a prospective, multicenter, randomized, double-blind, parallel-group, vehicle suspension-controlled study. 144 eligible subjects were randomly assigned in a 2:1 ratio; in one arm, subjects received 1 drop of an ophthalmic microsuspension containing 1.5% (w / v) dexamethasone, 3 times daily (every 8 hours) for 12 weeks (99 subjects), and in the other arm, subjects received vehicle eye drops 3 times daily (every 8 hours) for 12 weeks (45 subjects). The primary efficacy endpoint was the mean change in early treatment-derived diabetic retinopathy study (ETDRS) BCVA score at week 12 compared to baseline. Secondary endpoints included mean change in central macular thickness (CMT) as assessed by spectral-domain optical coherence tomography (SD-OCT) at weeks 2, 4, 8, 12, and 16 compared to baseline.Safety endpoints included AE, laboratory safety testing, slit-lamp examination parameters indicating ocular toxicity to the investigational drug, intraocular pressure, and dilated indirect ophthalmoscopy. Efficacy Results • Improved Corrected Visual Acuity At week 12, the mean change from baseline in the ETDRS BCVA letter score was greater in the arm evaluated with the as-described eye drop formulation than in the vehicle-only arm: 2.9 (70% CI: 2.13, 3.65) versus 1.7 (70% CI: 0.66, 2.72). The ANCOVA results supported the alternative hypothesis and established the superiority of the as-described dexamethasone-containing eye drop formulation over the vehicle-only eye drop with an alpha of 0.15. • Central macular thickness A greater reduction in mean CMT from baseline was observed in the arm tested with the eye drop formulation described compared to the vehicle arm up to week 12. From week 2 to week 12, a statistically highly significant mean LS difference was observed from baseline in the reduction of ocular CMT in favor of the tested arm; Mean LS difference at week 12; -36.77 (70% CI: -53.58, -19.95), p value = 0.01. The ANCOVA results adjusted to baseline with multiple imputation also showed superiority of the eye drop formulation over the Vehicle group in improving CMT at week 12 (with an alpha of 0.15). Safety results Treatment-emergent adverse events (TEAEs) were reported in a higher proportion of subjects in the group that received dexamethasone ophthalmic microsuspension than in subjects in the vehicle group (70 [70.0%] subjects experienced 134 TEAEs versus 24 [53.3%] subjects experienced 50 TEAEs). Severe adverse events (AEs) were reported in a higher proportion of subjects in the dexamethasone ophthalmic microsuspension group than in subjects in the vehicle group (11 [11.1%] subjects experienced 14 severe AEs versus 1 [2.2%] subject experienced 1 AE). In both treatment groups, these severe AEs were unrelated to the study medication. Clinical Study 2: Use of an aqueous pharmaceutical formulation of dexamethasone (1.5% w / v) in the treatment of pain and inflammation after cataract surgery This was a multicenter, randomized, double-masked, placebo-controlled (vehicle) study designed to evaluate the efficacy and safety of the eye drop formulation as described herein (containing 1.5% w / v dexamethasone) compared to placebo in the treatment of inflammation and pain following cataract surgery. Subjects were randomized 1:1:1 to receive the dexamethasone eye drop formulation once daily (QD) and placebo QD, twice daily (BID), or placebo BID. Subjects dosed 1 drop in the study eye BID for 14 days, beginning one day post-surgery in the operated eye. The primary hierarchical efficacy measures were 1) absence of anterior chamber cells (i.e., score of '0') at visit 6 (day 15) and 2) absence of pain (i.e., score of '0') at visit 4 (day 4). Safety measures included changes from baseline in pinhole VA (without any other correction) as measured on the ETDRS chart, changes from baseline in IOP, and adverse event (AE) rates. Efficacy results At visit 6 (day 15), the number of absent anterior chamber cells was significantly higher for QD (26 subjects with absent AC cells [51.0%], p = 0.0009) and BID (34 subjects with absent AC cells [66.7%], p < 0.0001) compared with placebo (10 subjects with absent AC cells [19.6%]). At visit 4, the number of subjects with no pain was significantly higher for QD (37 subjects [72.5%], p = 0.0049) and BID (32 subjects [62.7%], p = 0.0738) compared with placebo (23 subjects [45.1%]). Overall, the primary efficacy objective was achieved, and the results indicate that dosing with QD or BID is significantly superior to placebo in reducing the number of subjects with anterior chamber cells and the number of subjects with pain after cataract surgery. Safety results Overall, a higher proportion of TEAE, including ocular TEAE, was reported in the placebo group compared to either of the tested groups. The results indicate that the dexamethasone eye drop formulation as tested is safe and well tolerated. Example 6: Screening studies for the use of alternative antioxidants For the purposes of this study, a set of test formulations containing different amounts of antioxidants were prepared. The test formulations were prepared by adding a specific antioxidant, as listed in Table XX, to the formulation described in Table 1 of Example 1. The concentration of antioxidants was set as equimolar to 0.3% w / v sodium thiosulfate. The prepared test formulations were adjusted to pH 5 (4.9–5.1) and autoclaved twice under ambient air (without oxygen insertion). After the second autoclave cycles, the pH of the samples was measured. Information on the antioxidants used, their concentrations, and the pH measurement results are presented in Table 11. Table 11: Results of pH drop after 2x autoclave cycles Antioxidant Label Concentration used (w / v %) □H Initial After 2 autoclave cycles * Ref Formulation without antioxidant. NA 4.94 4.00 SA (+)-L-sodium ascorbate 0.38% 5.06 4.81 Cys Cysteine ​​0.23% 4.98 3.86 LA Lactic acid 0.17% 4.96 4.34 AP L-ascorbyl palmitate 0.79%** 5.06 3.58 SFS Sodium formaldehyde sulfoxylate 0.22% 5.01 3.62 LG Lauryl gallate 0.64%** 5.04 4.54 Met L-Methionine 0.28% 4.95 5.32 TBHQ tert-butylhydroquinone 0.32%** 5.06 4.27 TA DL-tartaric acid 0.28% 5.04 4.74 MA DL-malic acid 0.24% 4.96 4.83 MTG a-monothioqlicerol 0.21% 5.08 4.66 Sodium citrate tribasic dihydrate 0.48% 5.05 4.95 STS Sodium thiosulfate pentahydrate 0.30% 5.08 5.56 BHA Butylated hydroxyanisole 0.34%** 4.92 4.49 PCA 3,4-Dihydroxybenzoic acid 0.29% 4.99 4.97 *averaged from 2 measurements; **did not fully dissolve The antioxidants considered can be divided into several groups based on their effectiveness in stabilizing the formulation (see Table 12). Table 12. Classification of antioxidants considered according to their efficiency Group pH Drop Range (abs) Representatives A > 0 Sodium thiosulfate, L-Methionine, 3,4-Dihydroxybenzoic acid B 0-0.5 Tribasic sodium citrate, DL-malic acid, (+)-L-sodium ascorbate, DL-tartaric acid, α-monothioglycerol, butylated hydroxyanisole C 0.5-1.0 Lauryl gallate, lactic acid, tert-butylhydroquinone D 1.0-1.5 Cysteine, sodium formaldehyde sulfoxylate, L-ascorbyl palmitate Antioxidants from groups A, B, and C showed a positive effect on the pH stability of the formulation, while representatives from group D were useless. Discussion of the study results To facilitate the interpretation of the results obtained, the stress conditions of the described studies should be adopted as the conditions for the long-term stability program currently being implemented for an eye drop formulation. For this purpose, the pH drop values ​​for stock formulations stored in glass containers from the study were compared with the pH drop profile for a clinical batch stored at 25°C in antioxidant-free LDPE plastic containers (STS). The results of different heat stress tests revealed alternative antioxidants that can be used to inhibit the pH drop of the OCS-01 formulation during long-term storage. • Antioxidants such as L-methionine, 3,4-dihydroxybenzoic acid, sodium citrate, DL-malic acid, (+)-L-sodium ascorbate, DL-tartaric acid, α-monothioglycerol, lauryl gallate, lactic acid and tert-butylhydroquinone can stabilize the formulation for at least 1 year of storage at 25°C. • Covitol® 1100 EU, butylated hydroxyanisole, butylated hydroxytoluene and sodium thiosulfate can serve as suitable antioxidants for formulations with up to 2 years of storage at 25°C. • The maximum storage time during which the aforementioned antioxidants will remain effective was not studied and may exceed the storage time concluded above. In conclusion, among the antioxidants tracked, sodium thiosulfate was the best antioxidant for stabilizing the pH of the 1.5% dexamethasone ophthalmic suspension. Additional antioxidants provide a stabilizing profile for the 1.5% dexamethasone ophthalmic suspension. They may be less effective than STS in stabilizing pH, but can achieve stability for 2 years when stored at 25°C in a plastic / LDPE container. These antioxidants include L-methionine, 3,4-dihydroxybenzoic acid, sodium citrate, DL-malic acid, (+)L-sodium ascorbate, DL-tartaric acid, α-monothioglycerol, lauryl gallate, lactic acid, tert-butylhydroquinone, Covitol® 1100 EU (d-alpha-tocopherol acetate), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT).

Claims

1. A method for stabilizing the pH of an aqueous composition comprising a drug, said method comprising the addition of an additive to prevent oxidation of the drug.

2. The method according to claim 1, further characterized in that the aqueous composition comprises cyclodextrin, preferably gamma-cyclodextrin.

3. The method according to claim 1 or 2, further characterized in that the drug is a corticosteroid.

4. The method in accordance with any of the preceding claims, further characterized in that the drug is dexamethasone.

5. The method in accordance with any of the preceding claims, further characterized in that the additive for preventing oxidation of the drug is selected from antioxidants, oxygen scavengers and mixtures thereof.

6. The method in accordance with any of the preceding claims, further characterized in that the additive for preventing oxidation of the drug is selected from phenolic antioxidants, water-soluble natural antioxidants, or food antioxidants.

7. The method according to any of the preceding claims, further characterized in that the additive for preventing oxidation is selected from the group consisting of sodium thiosulfate, methionine, 3,4-dihydroxybenzoic acid, sodium citrate, malic acid, sodium ascorbate, tartaric acid, α-monothioglycerol, butylated hydroxyanisole, lauryl gallate, lactic acid, tert-butylhydroquinone and their salts or derivatives.

8. The method according to any of the preceding claims, further characterized in that the additive for preventing oxidation is selected from the group consisting of sodium thiosulfate, methionine (typically L-methionine), 3,4-dihydroxybenzoic acid, sodium citrate (e.g., tribasic dehydrated sodium citrate), malic acid (typically DL-malic acid), sodium ascorbate (e.g., (+)-L-sodium ascorbate), tartaric acid (typically DL-tartaric acid), α-monothioglycerol, and butylated hydroxyanisole.

9. The method according to any of the preceding claims, further characterized in that the additive for preventing oxidation is selected from the group consisting of sodium thiosulfate, methionine, and 3,4-dihydroxybenzoic acid.

10. The method according to any of the preceding claims, further characterized in that the additive for preventing oxidation is selected from the group consisting of sodium thiosulfate, methionine, and 3,4-dihydroxybenzoic acid.

11. The method in accordance with any of the preceding claims, further characterized in that the additive for preventing oxidation is sodium thiosulfate.

12. The method according to any of the preceding claims, further characterized in that the additive for preventing oxidation of the drug is added to the aqueous composition at a concentration of at least 0.05% (w / v), preferably at a concentration between 0.05% (w / v) and 1% (w / v), more preferably between 0.1 and 0.5%, and even more preferably between 0.2% (w / v) and 0.4% (w / v).

13. The method according to any of the preceding claims, further characterized in that the pH of the aqueous composition comprising a drug is between 4 and 8, preferably between 4.5 and 6.

14. An aqueous composition comprising a corticosteroid, cyclodextrin, preferably gamma-cyclodextrin, and an additive for preventing oxidation of the corticosteroid, wherein said additive is present in the composition at a concentration between 0.15% (w / v) and 0.6% (w / v), and preferably at a concentration between 0.2% (w / v) and 0.5% (w / v).

15. The composition according to claim 14, further characterized in that the corticosteroid is dexamethasone, typically 1.5% or 3.0% (w / v) dexamethasone.

16. The composition according to claim 14 or 15, further characterized in that the additive for preventing oxidation of the corticosteroid is selected from antioxidants, oxygen scavengers and mixtures thereof.

17. The composition according to any of claims 14 to 16, further characterized in that the additive for preventing oxidation of the corticosteroid is selected from phenolic antioxidants, water-soluble natural antioxidants, or food antioxidants.

18. The composition according to any of claims 14 to 17, further characterized in that the additive for preventing oxidation is selected from the group consisting of sodium thiosulfate, methionine, 3,4-dihydroxybenzoic acid, sodium citrate, malic acid, sodium ascorbate, tartaric acid, α-monothioglycerol, butylated hydroxyanisole, lauryl gallate, lactic acid, tert-butylhydroquinone and their salts or derivatives.

19. The composition according to any of claims 14 to 18, further characterized in that the oxidation-preventing additive is selected from the group consisting of sodium thiosulfate, methionine (typically L-methionine), 3,4-dihydroxybenzoic acid, sodium citrate (e.g., tribasic dehydrated sodium citrate), malic acid (typically DL-malic acid), sodium ascorbate (e.g., (+)-L-sodium ascorbate), tartaric acid (typically DL-tartaric acid), α-monothioglycerol, and butylated hydroxyanisole. MA / a / ZUZl / UlD / O / 20. The composition according to any of claims 14 to 19, further characterized in that the additive for preventing oxidation is selected from the group consisting of sodium thiosulfate, methionine and 3,4-dihydroxybenzoic acid.

21. The composition according to any of claims 14 to 20, further characterized in that the oxidation-preventing additive is selected from the group consisting of sodium thiosulfate, methionine, and 3,4-dihydroxybenzoic acid.

22. The composition according to any of claims 14 to 21, further characterized in that the additive for preventing oxidation is sodium thiosulfate.

23. The composition according to any of claims 14 to 22, further characterized in that the pH of the composition is between 4 and 8, preferably between 4.5 and 6.

24. The composition according to any of claims 14 to 23, further characterized in that it is a microsuspension, preferably comprising 80% to 95% of the corticosterol in microparticles having a diameter of 1 µm to 10 µm.

25. The composition according to any of claims 14 to 24 for use in the treatment of an eye condition, in particular an anterior eye condition or a posterior eye condition.

26. The composition according to any of claims 14 to 25, further characterized in that said corticosteroid is dexamethasone, for use in the treatment of central retinal vein occlusion or eye inflammations.

27. The composition according to any of claims 14 to 25, further characterized in that said corticosteroid is dexamethasone, for use in the treatment of diabetic macular edema; or inflammation following eye surgery, typically following cataract surgery; 28. The use of an additive to prevent the oxidation of a corticosteroid to stabilize the pH of an aqueous composition comprising a corticosteroid, in particular an aqueous composition comprising dexamethasone / gamma-cyclodextrin complexes.