OPHTHALMIC COMPOSITIONS IN FORM OF AQUEOUS GELS

Abstract: Ophthalmic preparations are described in form of aqueous gels with a viscosity range between 400 and 800 cps including: at least one active principle; a gelling agent and at least 2 co-solubilising/co-gelling agents.

Description: OPHTHALMIC COMPOSITIONS IN FORM OF AQUEOUS GELS The present invention relates to ophthalmic compositions in form of aqueous gels. The pharmacological therapy of ocular pathologies by topical administration may appear as a simple problem if many peculiar elements of the ocular structure, ,- which make it of pharmaceutically difficult treatment, are not considered. Not considering the pathology and, therefore, the adequate active principle, the mostly influencing variables to optimise this kind of therapy are the following: physiological/anatomical aspects; the administered quantity of active principle in the form of homogeneous aqueous solution or suspension ι n (conventional eye drops) quickly leaves the interested area either by blinking and/or lacrimal drainage. Just a small percentage of the administered preparation is retained in the corneal region, and can develop, after absorption, a pharmacological action. "barrier" effect to absorption, induced by different tissues/components _. , (cornea, conjunctiva, tear film etc.) influencing the active principle distribution in the different compartments of the anterior section of the eye. In the last years, to solve the above mentioned problems, many strategies have been carried out , based on: 1) the chemical structure of the active principle (more addressed to ^ π hydrophilic/lipophilic ratio), therefore trying to increase absorption - in the cornea, conjunctiva etc. - of the slight residual quantity, after blinking; 2) the weight increase of the active principle in the formulations, with consequent higher risk of adverse effects; 3) the increase of the daily posology (up to 6/8 daily ,c administrations) with reduction of patient compliance; 4) the change of the vehicle used in the pharmaceutical preparations. As far as the latter point is concerned, the rational of different approaches, made up to now, consists in the hypothesis that an increase of residence time in the ocular milieu (cornea, conjunctiva) of the blinking-resistant residual dose should lead to an increase of therapeutical efficacy, due to high potential availability of the active principle absorption. To reach this target different strategies have been adopted: i) use of solid devices with slow releasing effects to be placed in the cul-de-sac (scarcely accepted by the patient); ii) use of formulations characterised by a more or less high viscosity (mostly used approach). Disregarding the use of eye ointments based on fat vehicles, whose limited compliance is well-known , the approach to viscous formulations can be divided into: i) use of preformed aqueous vehicles of appropriate viscosity, to be administered as such; ii) use of suitable solutions, gelling in contact with ocular surface (for example by variation of temperature, pH or ionic strength). US3,920,810 (18/11/1975), to Burton Parson & Co., claims low viscosity ophthalmic solutions, using polyacrylamide as first agent and, optionally, polyethylene glycol as wetting and plasticizer agent. These solutions can be used as artificial tears or as cleaning and hydrating liquids for contact lenses, or as vehicles for chemically alkaline or neutral active substances. In this latter case, the following additives are suggested but, are not considered essential: - water-soluble cellulose derivatives, like hydroxymethylcellulose as buffer agents and viscosity stabilising agents; polyvinylpirrolidone, as "detoxicant" of lacrimal film and spreading agent; biocides etc. The viscosity of these solutions ranges between 10 and 200 cps, while the high residence time, compared with that of conventional eye drops, seems to be triplicated (even quadruplicated); the comparison between a pilocarpine preparation and one in the form of traditional eye drops leads to similar therapeutic results, with a slightly reduction of the dosage (3 adm./day vs 4 adm./day). FR76358076 (Alcon Laboratories) discloses solutions used as artificial tears, for dry eye syndrome treatment; these solutions show low viscosity and contain polysaccharides such as dextrans or arabinogalactans and polyethylene glycols. EP-B-227494 (02/10/1986, Laboratories Merk, Sharp & Dohme-Chibret) discloses polysaccharide liquid preparations which, under the effect of a ionic strength variation (ocular milieu salinity), undergo transition to high or low viscosity. The used polysaccharide is a heteropolysaccharide produced by the Pseudomonas Elodea bacterium, known as gellan gum or its modifications. The formulations are useful in the treatment of dry eye syndrome or as drug delivering systems. Said formulations show a residence time about twice that obtained by a traditional aqueous preparation. The comparison between two compositions, with the same concentration (0.25%) of timolol (a non-gelling commercial one and the other containing a vehicle described in EP-B-227494), shows that on checking times (30;60; 120; 180 minutes) the active principle concentration of the commercial preparation in the rabbit lacrimal fluid is 3 (30;60; 120 minutes) to two times (180 min.) versus the disclosed composition. A drawback could consists in the fact that the optimal active substances should be soluble in water, while the non soluble substances have to be used in suspensions or in emulsions. WO 91/19481 (1 1/06/91 Allergan Inc.) discloses solutions reversibly gelling upon simultaneous variations of, at least, two physical parameters, such as temperature, pH or ionic strength. These solutions, suitable for topical or sistemic formulations, consist of a methylcellulose and polyacrylic acid mixture in the presence or in the absence of inorganic salts. These drug vehicles can carry active substances in solutions or in dispersion. The final, local values of lacrimal fluid viscosity, formed after gelling, should be very high, considering that initial values ranged from 3000 cP to 16,000 cP and more, even if they are defined easily flowing in drops. The residence time and the distribution have been studied by the fluoresceine test or FITC-dextran test, with the following conclusions: i) formation of a gelatinous deposit in the lower part of the cul-de-sac, ii) formation of a regular-looking, thin film on the conjunctival-corneal region. These results show that an important part of the composition remains in an ocular site of low absorption capacity, where, moreover, the elimination by lacrimal drainage is easier (the residence time in the eye has been evaluated of about 3 hours, whereas the one of the film would be twice longer). WO 93/17664 (Alcon lab.) discloses ophthalmic preparations useful per se as drugs for the dry eye syndrome treatment (artificial tears) and as active substances delivery vehicles for different ocular pathologies; these preparations are combinations of aqueous mixtures of viscosity-increasing agents (i.e. carboxyvinyl polymers and non-carboxylated cellulose polymers), which result more viscous than the single component - preparations, the patent claims (but does not exemplify) the use of polyethylene glycol or polyvinyl alcohol only in the case of artificial tears. Consequently it appears that, excluding the auto-gelling preparations, the viscosity increase can be desirable in artificial tears (dry eye syndrome treatment), but not in order to increase bioavailability of the active substance (and therefore the therapeutic efficacy of a preparation), due to the poor patient compliance towards vehicles with higher viscosity, and to the easier elimination of the drug by blinking or lacrimal drainage in the case of low viscosity vehicles. Moreover, the higher costs of manufacturing are a negative element for the competition with conventional eye drops. DISCLOSURE OF THE INVENTION. It has been found that ophthalmic compositions in the form of aqueous gels, characterised by the presence of at least 3 components selected from gelling agents and co-solvents/co-gelling agents, are particularly effective and well tolerated. Particularly, the compositions of the invention provide, under similar conditions, the same level of reduction of clinical symptoms, or of cure, obtained by conventional eye drops, even using: reduced concentrations of active principles; 50% to 70% reduced posology (for example from 4-6 adm./day to 2 adm./day). These favourable effects cannot be explained only according to the theory of the residence time increase, related to a rise in vehicle viscosity. The compositions of the invention provide the following advantages: a uniform distribution of the administered gel, expecially on the conjunctival region of the cornea, which is the most absorbing zone and, at the same time, an important depot for topically applied drugs. (Reddy I.K. et al. In "Ocular Therapeutic and Drug delivery" - I.K.Reddy Ed.-Technomic Publ., 1996,1-23); an optimal adhesion of the film to the corneal and bulbar conjunctival structures; a particularly high stabilisation of the above mentioned film, suitable to prevent its rupture and consequently its (partial or total) elimination by lacrimal drainage or its displacement in the lower cul-de-sac zone, where absorption for ocular therapeutical aims is reduced. The physiological combination of the vehicle (therefore of the active principle) and lacrimal film, without change of its capability to adhere to the cornea and bulbar conjunctiva, could be the basis of the above described advantages. DETAILED DISCLOSURE OF THE INVENTION The invention relates to ophthalmic compositions in the form of aqueous gels with a range of viscosity from 400 to 800 cps, containing: at least one active principle, - a gelling agent, at least two co-solubilising/co-gelling agents. Examples of active principles that can be adequately formulated according to the invention include: antibiotic/antibacterial agents (gentamicin, tobramycin and similar ones; chloramphenicol, etc.), antimicotics (miconazole, econazole and similar ones), steroidal and non-steroidal anti-inflammatories (budesonide, diclofenac, niflumic acid, betamethasone and others), beta-blocker such as timolol, etc. Acrylic acid polymers, sodium carboxymethylcellulose, hydroxymethylcellulose, and/or these mixtures are preferably used as gelling agents. Among the acrylic acid polymers, Carbomer 940 and 980 are preferably used. The weight percentages of gelling agents in the final formulations are the following: acrylic acid polymers: from 0.1 to 0.7%, preferably from 0.2 to 0.3%; sodium carboxymethylcellulose: from 1.5 to 3%, preferably from 2 to 2.5%; - hydroxymethylcellulose: from 0.5 to 3%, preferably from 1 to 1.5%. The co-solubilising/co-gelling agents, according to the invention, are selected from: polyethylene glycol (molecular weight between 200 and 500 approx., preferably approx. 300: PEG 300), polyethoxylated hydrogenated castor oil derivatives (Cremophor RH®) and polyvinyl alcohol. This latter is mainly a co-gelling agent; Cremophor RH is a co-solubilising agent, while PEGs can be considered both co-gelling and co-solubilising agents. The weight percentages of co-gelling/co-solubilising agents on final formulations are the following ones: PEG, particularly for PEG 300, from 4 to 10%; Cremophor RH: from 0.5 to 20%, preferably from 2 to 10% and, more preferably, from 2 to 6%; polyvinyl alcohol: from 0.4% to 0.5%, preferably 0.4%. Examples of formulations of this invention could include: i) PEG 300 as co- solubilising agent, Carbomer as gelling agent and PVA as co-gelling agent; ii) PEG 300 and Cremophor RH as co-solubilising/co-gelling agent and sodium carboxymethylcellulose as gelling agent; iii) PEG300 and Cremophor RH as co- solubilising/co-gelling agents and hydroxyethylcellulose as gelling agent. The following examples show the details of this invention: COMPOSITION NO. 1A (steroidal anti-inflammatory / antibiotic) Active principles: Betamethasone 21 -phosphate 0.066 g (equivalent to Betamethasone 0.05%) Chloramphenicol 0.250 g Excipients: Polyethylene Glycol 300 6.500 g Polyvinyl Alcohol 0.500 g Carbomer * 0.290 g Sodium Edetate 0.100 g Sodium Merthiolate 0.002 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g * Carbopol 980 COMPOSITION N O. IB (steroidal anti-inflammatory / antibiotic ) Active principles: Betamethasone 21 -phosphate 0.132 g (equivalent to Betamethasone 0.1%) Chloramphenicol 0.250 g Excipients: Polyethylene Glycol 300 6.500 g Polyvinyl Alcohol 0.500 g Carbomer * 0.290 g Sodium Edetate 0.100 g Sodium Merthiolate 0.002 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g * Carbopol 980 COMPOSITION NO. IC ( steroidal anti -inflammatory / antibiotic ) Active principles: Betamethasone 21 -phosphate 0.066 g (equivalent to Betamethasone 0.05%) Chloramphenicol 0.250 g Excipients: Polyethylene Glycol 300 6.500 g Polyvinyl Alcohol 0.400 g Polyxil 40 hydrogenated castor oil 1} 0.100 g Carbomer 2) 0.290 g Sodium Edetate 0.100 g Sodium Merthiolate 0.002 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g 1} Cremophor RH40 2) Carbopol 980 COMPOSITION NO. ID (steroidal anti- •inflammatory / antibiotic ) Active principles: Betamethasone 21 -phosphate 0.132 g (equivalent to Betamethasone 0.1 %) Chloramphenicol 0.250 g Excipients: Polyethylene Glycol 300 6.500 g Polyvinyl Alcohol 0.400 g Polyxil 40 hydrogenated castor oil n 0.100 g Carbomer 2) 0.290 g Sodium Edetate 0.100 g Sodium Merthiolate 0.002 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g !) Cremophor RH40 2) Carbopol 980 COMPOSITION NO. 2A (non steroidal anti - inflammatory) Active principle: Diclofenac Sodium 0.050 g Excipients: Polyethylene Glycol 300 6.500 g Polyvinyl Alcohol 0.500 g Carbomer * 0.290 g Sodium Edetate 0.100 g Sodium Merthiolate 0.002 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g * Carbopol 980 COMPOSITION NO. 2B (non steroidal anti -inflammatory) Active principle: Diclofenac Sodium 0.100 g Excipients: Polyethylene Glycol 300 6.500 g Polyvinyl Alcohol 0.500 g Carbomer * 0.290 g Sodium Edetate 0.100 g Sodium Merthiolate 0.002 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g * Carbopol 980 COMPOSITION NO. 2C (non steroidal anti- inflammatory) Active principle: Diclofenac Sodium 0.050 g Excipients: Polyethylene Glycol 300 6.400 g Polyxil 40 hydrogenated castor oil 1 } 0.100 g Polyvinyl Alcohol 0.500 g Carbomer 2) 0.290 g Sodium Edetate 0.100 g Sodium Merthiolate 0.002 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g l ) Cremophor RH40 2) Carbopol 980 COMPOSITION NO. 2D (non steroidal anti-inflammatory) Active principle: Diclofenac Sodium 0.100 g Excipients: Polyethylene Glycol 300 6.400 g Polyxil 40 hydrogenated castor oil 1} 0.100 g Polyvinyl Alcohol 0.500 g Carbomer 2) 0.290 g Sodium Edetate 0.100 g Sodium Merthiolate 0.002 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g !) Cremophor RH40 2) Carbopol 980 COMPOSITION NO. 3A (non steroidal anti-inflammatory ) Active principle: Niflumic Acid 0.500 g Excipients: polyethylene Glycol 300 6.500 g Sodium Carboxymethylcellulose 2.500 g Sodium Chloride 0.570 g Polyxil 40 hydrogenated castor oil* 0.500 g Sodium Merthiolate 0.002 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. 100.000 g * Cremophor RH-40 COMPOSITION NO. 3B (non steroidal anti- -inflammatory) Active principle: Niflumic Acid 1.000 g Excipients: Polyethylene Glycol 300 6.500 g Sodium Carboxymethylcellulose 2.500 g Sodium Chloride 0.570 g Polyxil 40 hydrogenated castor oil * 0.500 g Sodium Merthiolate 0.002 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 ; * Cremophor RH-40 COMPOSITION NO. 4A (Antifunεan Active principle: Miconazole 0.300 g Excipients: Polyethylene Glycol 300 10.000 g Polyoxil 40 hydrogenated castor oil * 6.000 g Sodium Carboxymethylcellulose 2.500 g Gluconic Acid 0.150 g Cetrimide 0.010 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g * Cremophor RH-40 COMPOSITION NO. 4B (Antifunεan Active principle: Miconazole 0.500 g Excipients: Polyethylene Glycol 300 10.000 g Polyoxil 40 hydrogenated castor oil* 6.000 g Sodium Carboxymethylcellulose 2.500 g Gluconic Acid 0.250 g Cetrimide 0.010 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g * Cremophor RH40 COMPOSITION NO. 5A (Anti-εlaucoma Active principle: Timolol maleate 0.342 g (equivalent to Timolol 0.25 %) Excipients: Polyethylene Glycol 300 3.000 g Sodium Carboxymethylcellulose 2.000 g Polyoxil 40 hydrogenated castor oil * 2.000 g Sodium Chloride 0.165 g Sodium Edetate 0.100 g Benzalkonium Chloride 0.010 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g * Cremophor RH40 COMPOSITION NO. 5B (Anti-glaucoma) Active principle: Timolol maleate 0.684 g (equivalent to Timolol 0.50 %) Excipients: Polyethylene Glycol 300 3.000 g Sodium Carboxymethylcellulose 2.000 g Polyoxil 40 hydrogenated castor oil * 2.000 g Sodium Chloride 0.165 g Sodium Edetate 0.100 g Benzalkonium Chloride 0.010 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g * Cremophor RH40 COMPOSITION NO. 6 (Antibiotic / non steroidal anti-inflammatory) Active principles: Diclofenac Sodium 0.100 g Tobramycin 0.300 g Excipients: Polyethylene Glycol 300 4.000 g Polyoxil 40 hydrogenated castor oil * 2.000 g Cellulose Hydroxyethyl 1.500 g Sodium Chloride 0.800 g Cetrimide 0.010 g Hydrogen Chloride q.s. to pH 7.0 Purified water q.s. to 100.000 g * Cremophor RH40 COMPOSITION NO. 7A (Antibiotic Active principle: Gentamicin Sulphate 0.250 g (equivalent to Gentamicin 0.15%) Excipients: Polyethylene Glycol 300 4.000 g Cellulose Hydroxyethyl 1.500 g Sodium Phosphate Dibasic 0.630 g Polyoxil 40 hydrogenated castor oil * 0.500 g Sodium Chloride 0.500 g Sodium Phosphate Monobasic 0.170 g Sodium Edetate 0.100 g Sodium Metabisulfite 0.100 g Benzalkonium Chloride 0.010 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g * Cremophor RH40 COMPOSITION NO. 7B (Antibiotic) Active principle: Gentamicin Sulphate 0.500 g (equivalent to Gentamicin 0.3%) Excipients: Polyethylene Glycol 300 4.000 g Cellulose Hydroxyethyl 1.500 g Sodium Phosphate Dibasic 0.630 g Polyoxil 40 hydrogenated castor oil * 0.500 g Sodium Chloride 0.500 g Sodium Phosphate Monobasic 0.170 g Sodium Edetate 0.100 g Sodium Metabisulfite 0.100 g Benzalkonium Chloride 0.010 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g * Cremophor RH40 COMPOSITION NO. 8A (Anti-glaucoma) Active principle: Timolol maleate 0.342 g (equivalent to Timolol 0.25 %) Excipients: Polyethylene Glycol 300 3.000 g Polyoxil 40 hydrogenated castor oil * 2.000 g Cellulose Hydroxyethyl 1.200 g Sodium Chloride 0.280 g Sodium Edetate 0.100 g Benzalkonium Chloride 0.010 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g * Cremophor RH40 COMPOSITION NO. 8B (Anti-glaucoma) Active principle: Timolol maleate 0.684 g (equivalent to Timolol 0.50 %) Excipients: Polyethylene Glycol 300 3.000 g Polyoxil 40 hydrogenated castor oil * 2.000 g Cellulose Hydroxyethyl 1.200 g Sodium Chloride 0.280 g Sodium Edetate 0.100 g Benzalkonium Chloride 0.010 g Sodium Hydroxide q.s. to pH 7.0 Purified water q.s. to 100.000 g * Cremophor RH40

Claims: CLAIMS 1. Ophthalmic compositions in the form of aqueous gel with a viscosity range between 400 and 800 cps, comprising: - one active principle; a gelling agent and at least two co-solubilising/co-gelling agents. 2. Compositions as claimed in claim 1, wherein the gelling agent is selected from acrylic acid polymers, sodium carboxymethylcellulose, hydroxyethilcellulose. 3. Compositions as claimed in claim 1 or 2, wherein the co-solubilising/co- gelling agent is selected from a polyethylene glycol with molecular weight ranging from 200 to 500, polyethoxylated derivatives of hydrogenated castor oil (Cremophor RH40), polyvinyl alcohol. 4. Compositions as claimed in any one of the above claims wherein the acrylic acid polymer is Carbomer 980. 5. Compositions as claimed in any one of the above claims wherein one of the two co-solubilising/co-gelling agents is PEG300. 6. Compositions as claimed in claim 5 wherein the other co-solubilising/co- gelling agents is Cremophor RH40. 7. Compositions as claimed in claim 6 wherein the other co-solubilising/co- gelling is polyvinyl alcohol. 8. Compositions as claimed in any one of the above claims, containing an ophthalmically useful active principle selected from antibiotics, antibacterials, antimicotics, steroidal or non steroidal anti-inflammatories, beta-blockers.

Inventors: SANSO' MARCO, SEBBEN RENATO, SANSO', MARCO, SEBBEN, RENATO
Applicants: FARMILA FARMA MILANO, SANSO MARCO, SEBBEN RENATO, FARMILA FARMACEUTICI MILANO S.P.A., SANSO', MARCO, SEBBEN, RENATO
Application year: 2000
Main classification: A61K9
IPC codes: A61K9, A61P9, A61P29, A61P31