Title:  Compositions containing therapeutically active components having enhanced solubility

United States Patent:  6,562,873

Issued:  May 13, 2003

Inventors:  Olejnik; Orest (Coto de Coza, CA); Kerslake; Edward D. S. (Charleston, MA)

Assignee:  Allergan, Inc. (Irvine, CA)

Appl. No.:  903962

Filed:  July 10, 2001

Compositions which include therapeutically active components, solubility enhancing components other than cyclodextrins, and oxy-chloro components, wherein the oxy-chloro components are substantially effective as preservatives. In one embodiment, the oxy-chloro components are useful for preserving the therapeutically active components. In one embodiment, the oxy-chloro components include chlorite components. In a useful embodiment, the solubility enhancing components include carboxymethylcellulose.

DETAILED DESCRIPTION OF THE INVENTION

Compositions comprising TACs, SECs and oxy-chloro components are provided. The TACs in the present compositions are made more soluble and may be more effectively utilized as therapeutic agents. Suitable SECs for solubilizing TACs may be used concurrently with oxy-chloro components in the present compositions to increase the solubility of the TACs substantially without detrimentally affecting the preservative effectiveness of the oxy-chloro components. In other words, SECs employed in the present compositions may effectively increase the solubility of TACs without substantially interfering with the functions of other components in the compositions. The SECs employed in the present compositions may be effective in the solubilization of ionized TACs, unionized TACs or both.

Oxy-chloro components are included in the present compositions to assist in preserving the compositions. Particularly, the oxy-chloro components are not substantially detrimentally affected by the SECs present in the compositions. Moreover, the oxy-chloro components in the compositions are effective substantially without causing undue harm or irritation to the tissue to which the present compositions are administered.

The present compositions may, and preferably do, include liquid carrier components. For example, the components often have the characteristics of a liquid, for example, a liquid solution.

The presently useful TACs preferably are chosen to benefit from the presence of the SECs and the oxy-chloro components. In general, the TACs are provided with increased apparent solubility, preferably increased apparent water solubility, by the presence of the SECs.

Preferably, the TACs have increased solubility in the present compositions at pH's greater than 7, as compared to identical TACs, at comparable concentrations in similar compositions, without the SECs. More preferably, the TACs have increased solubility in the present compositions at pH's in the range of about 7 to about 10, as compared to TACs in similar compositions, at comparable concentrations, without the SECs.

Without wishing to be limited by any theory or mechanism of operation, it is believed that solubilized TACs are better able to cross the lipid membranes relative to unsolubilized TACs. It is further believed that the solubilized TACs are physically smaller and are therefore more able to physically permeate or diffuse through the lipid membranes.

In one embodiment, the SECs of this invention are capable of solubilizing the TACs in the environments into which they are introduced at therapeutically effective concentrations. Preferably, the biological environments into which the present compositions are introduced have pH's ranging from about 7 to about 9. For example, a composition comprising a SEC and a TAC may be administered to the cornea of a human eye, which has a pH of about 7, wherein the TAC is substantially solubilized at the administered area. Furthermore, in one embodiment, the TACs solubilized by SECs at the administered area diffuse through biological lipid membranes more readily than TACs which are not solubilized by SECs. The solubilization of TACs preferably reduces irritation to sensitive tissues in contact or interacting with the TACs.

Examples of the therapeutically active components which may be included in the present compositions include, but are not limited to, antibacterial substances such as beta-lactam antibiotics, such as cefoxitin, n-formamidoylthienamycin and other thienamycin derivatives, tetracyclines, chloramphenicol, neomycin, carbenicillin, colistin, penicillin G, polymyxin B, vancomycin, cefazolin, cephaloridine, chibrorifamycin, gramicidin, bacitracin and sulfonamides; aminoglycoside antibiotics such as gentamycin, kanamycin, amikacin, sisomicin and tobramycin; nalidixic acid and its analogs such as norfloxacin and the antimicrobial combination fluoroalanine/pentizidone, nitrofurazones and analogs thereof; antihistaminics and decongestants such as pyrilamine, chlorpheniramine, tetrahydrazoline, antazoline and analogs thereof; mast-cell inhibitors of histamine release, such as cromolyn; anti-inflammatories such as cortisone, hydrocortisone, hydrocortisone acetate, betamethasone, dexamethasone, dexamethasone sodium phosphate, prednisone, methylprednisolone, medrysone, fluorometholone, prednisolone, prednisolone sodium phosphate, triamcinolone, indainethacin, sulindac, its salts and its corresponding sulfides, and analogs thereof; miotics and anticholinergics such as echothiophate, pilocarpine, physostigmine salicylate, diisopropylfluorophosphate, epinephrine, dipivaloylepinephrine, neostigmine echothiopate iodide, demecarim bromide, carbamoyl choline chloride, methacholine, bethanechol, and analogs thereof; mydriatics such as atrophine, homatropine, scopolamine, hydroxyamphetamine, ephedrine, cocaine, tropicamide, phenylephrine, cyclopentolate, oxyphenonium, eucatropine; and the like and mixtures thereof.

Other TACs are: antiglaucama drugs, for example, timalol, and especially its maleic salt and R-timolol and a combination of timolol or R-timolol with pilocarpine; other adrenergic agonists and/or antagonists such as epinephrine and an epinephrine complex, or prodrugs such as bitartrate, borate, hydrochloride and dipivefrine derivatives; carbonic anhydrase inhibitors such as acetazolamide, dichlorphenamide, 2-(p-hydroxyphenyl)-thiothiophenesulfonamide, 6-hydroxy-2-benzothiazolesulfonamide, and 6-pivaloyloxy-2-benzothiazolesulfonamide; antiparasitic compounds and/or anti-protozoal compounds such as ivermectin, pyrimethamine, trisulfapidimidine, clindamycin and corticosteroid preparations; compounds having antiviral activity such as acyclovir, 5-iodo-2'-deoxyuridine (IDU), adenosine arabinoside (Ara-A), trifluorothymidine, interferon, and interferon-inducing agents such as poly I:C; antifungal agents such as amphotericin B, nystatin, flucytosine, natamycin and miconazole; anesthetic agents such as etidocaine cocaine, benoxinate, dibucaine hydrochloride, dyclonine hydrochloride, naepaine, phenacaine hydrochloride, piperocaine, proparacaine hydrochloride, tetracaine hydrochloride, hexylcaine, bupivacaine, lidocaine, mepivacaine and prilocaine; ophthalmic diagnostic agents, such as: (a) those used to examine the retina such as sodium fluorescein, (b) those used to examine the conjunctiva, cornea and lacrimal apparatus, such as fluorescein and rose bengal and (c) those used to examine abnormal pupillary responses such as methacholine, cocaine, adrenaline, atropine, hydroxyamphetamine and pilocarpine; ophthalmic agents used as adjuncts in surgery, such as alpha-chymotrypsin and hyaluronidase; chelating agents such as ethylenediaminetetraacetic acid (EDTA) and deferoxamine; immunosuppressants and anti-metabolites such as methotrexate, cyclophosphamide, 6-mercaptopurine and azathioprine and combinations of the compounds mentioned above, such as antibiotics/antiinflammatories combinations such as the combination of neomycin sulfate and dexamethasone sodium phosphate and combinations concomitantly used for treating glaucoma, for example, a combination of timolol maleate and aceclidine; and the like and mixtures thereof.

In a preferred embodiment, the useful TACs include adrenergic agonists. The adrenergic agonists preferably are molecules containing amines. Also, the adrenergic agonists preferably are amine-containing molecules with pKa's of greater than 7, preferably about 7 to about 9.

More preferably, the useful TACs include alpha-adrenergic agonists. Examples of alpha-adrengergic agonists include, but not limited to, adrafinil, adrenolone, amidephrine, apraclonidine, budralazine, clonidine, cyclopentamine, detomidine, dimetofrine, dipivefrin, ephedrine, epinephrine, fenoxazoline, guanabenz, guanfacine, hydroxyamphetamine, ibopamine, indanazoline, isometheptene, mephentermine, metaraminol, methoxamine, methylhexaneamine, metizolene, midodrine, naphazoline, norepinephrine, norfenefrine, octodrine, octopamine, oxymetazoline, phenylephrine, phenylpropanolamine, phenylpropylmethylamine, pholedrine, propylhexedrine, pseudoephedrine, rilmenidine, synephrine, tetrahydrozoline, tiamenidine, tramazoline, tuaminoheptane, tymazoline, tyramine, xylometazoline, and the like and mixtures thereof.

In a still more preferred embodiment, the useful TACs include alpha-2-adrenergic agonists. As used herein, the term "alpha-2 adrenergic agonist" includes chemical entities, such as compounds, ions, complexes and the like, that produces a net sympatholytic response, resulting in increased accommodation, for example, by binding to presynaptic alpha-2 receptors on sympathetic postganglionic nerve endings or, for example, to postsynaptic alpha-2 receptors on smooth muscle cells. A sympatholytic response is characterized by the inhibition, diminishment, or prevention of the effects of impulses conveyed by the sympathetic nervous system. The alpha-2 adrenergic agonists of the invention bind to the alpha-2 adrenergic receptors presynaptically, causing negative feedback to decrease the release of neuronal norepinephrine. Additionally, they also work on alpha-2 adrenergic receptors postsynaptically, inhibiting beta-adrenergic receptor-stimulated formation of cyclic AMP, which contributes to the relaxation of the ciliary muscle, in addition to the effects of postsynaptic alpha-2 adrenergic receptors on other intracellular pathways. Activity at either pre- or postsynaptic alpha-2 adrenergic receptors will result in a decreased adrenergic influence. Decreased adrenergic influence results in increased contraction resulting from cholinergic innervations. Alpha-2 adrenergic agonists also include compounds that have neuroprotective activity. For example, 5-bromo-6-(2-imidozolin-2-ylamino) quinoxaline is an alpha-2-adrenergic agonist which has a neuroprotective activity through an unknown mechanism.

Without limiting the invention to the specific groups and compounds listed, the following is a list of representative alpha-2 adrenergic agonists useful in this invention: imino-imidazolines, including clonidine, apraclonidine; imidazolines, including naphazoline, xymetazoline, tetrahydrozoline, and tramazoline; imidazoles, including detomidine, medetomidine, and dexmedetomidine; azepines, including B-HT 920 (6-allyl-2-amino-5,6,7,8 tetrahydro-4H-thiazolo[4,5-d]-azepine and B-HT 933; thiazines, including xylazine; oxazolines, including rilmenidine; guanidines, including guanabenz and guanfacine; catecholamines and the like.

Particularly useful alpha-2-adrenergic agonists include quinoxaline components. In one embodiment, the quinoxaline components include quinoxaline, derivatives thereof and mixtures thereof. Preferably, the derivatives of quinoxaline include (2-imidozolin-2-ylamino) quinoxaline. More preferably, the derivatives of quinoxaline include 5-halide-6-(2-imidozolin-2-ylamino) quinoxaline. The "halide" of the 5-halide-6-(2-imidozolin-2-ylamino) quinoxaline may be a fluorine, a chlorine, an iodine, or preferably, a bromine, to form 5-bromo-6-(2-imidozolin-2-ylamino) quinoxaline. Even more preferably, the derivatives of quinoxaline to be used in accordance with this invention include a tartrate of 5-bromo-6-(2-imidozolin-2-ylamino) quinoxaline, or Brimonidine tartrate.

Other useful quinoxaline derivatives are well known. For example, useful derivatives of a quinoxaline include the ones disclose by Burke et al U.S. Pat. No. 5,703,077. See also Danielwicz et al 3,890,319. Each of the disclosures of Burke et al and Danielwicz et al is incorporated in its entirety by reference herein.

The quinoxaline and derivatives thereof, for example Brimonidine tartrate, are amine-containing and preferably have pKa's of greater than 7, preferably about 7.5 to 9.

Analogs of the foregoing compounds that function as alpha-2 adrenergic agonists also are specifically intended to be embraced by the invention.

Preferably, the alpha-2-adrenergic agonists, for example the ones listed above, are effective toward activating one or more of alpha-2A-adrenergic receptors, alpha-2B-adrenergic receptors and alpha-2D-adrenergic receptors.

Other useful TACs include ocular hypotensive agents (Woodward et al U.S. Pat. No. 5,688,819), cyclosporins (Ding et al U.S. Pat. No. 5,474,979), androgen tears (Sullivan U.S. Pat. No. 5,620,921), pyranoquinolinone derivatives (Cairns et al U.S. Pat. No. 4,474,787), compounds having retinoid-like activities (Chandraratna U.S. Pat. No. 5,089,509), ketorolac/pyrrole-1-carboxylic acids (Muchowski et al U.S. Pat. No. 4,089,969), ofloxacins/benzoxazine derivatives (Hayakawa et al U.S. Pat. No. 4,382,892), memantines (Lipton et al U.S. Pat. No. 5,922,773), RAR antagonists (Klein et al U.S. Pat. No. 5,952,345), RAR-alpha agonists (Teng et al U.S. Pat. No. 5,856,490). Each of the disclosures referred to in the above patents is incorporated in its entirety herein by reference.

In one embodiment, the TACs, for example Brimonidine tartrate, are substantially unionized in the composition. In another embodiment, the TACs are substantially unionized in the environment to which they are administered, for example the cornea of the human eye. Without wishing to be limited by any theory or mechanism of action, it is believed that the unionized forms of the TACs facilitate their permeation across membrane lipid bilayers.

Any suitable SEC, other than cyclodextrin, may be employed in accordance with the present invention. In one embodiment, the SECs include pyrrolinidone components. Examples of pyrrolinidone components are polyvinylpyrrolinidones, derivatives thereof and mixtures thereof. In a preferred embodiment, the SECs include polyanionic components. The useful polyanionic components include, but are not limited to, those materials which are effective in increasing the apparent solubility, preferably water solubility, of poorly soluble TACs and/or enhance the stability of the TACs and/or reduce unwanted side effects of the TACs. Furthermore, the polyanionic component is preferably ophthalmically acceptable at the concentrations used. Additionally, the polyanionic component preferably includes three (3) or more anionic (or negative) charges. In the event that the polyanionic component is a polymeric material, it is preferred that each of the repeating units of the polymeric material include a discrete anionic charge. Particularly useful anionic components are those which are water soluble, for example, soluble at the concentrations used in the presently useful liquid aqueous media, such as a liquid aqueous medium containing the polyanionic component and chlorite component.

The polyanionic component is preferably sufficiently anionic to interact with the TAC. Such interaction is believed to be desirable to solubilize the TAC and/or to maintain such TAC soluble in the carrier component, for example a liquid medium.

Polyanionic components also include one or more polymeric materials having multiple anionic charges. Examples include:

metal carboxymethylstarchs

metal carboxymethylhydroxyethylstarchs

hydrolyzed polyacrylamides and polyacrylonitriles

heparin

homopolymers and copolymers of one or more of:

acrylic and methacrylic acids

metal acrylates and methacrylates

alginic acid

metal alginates

vinylsulfonic acid

metal vinylsulfonate

amino acids, such as aspartic acid, glutamic acid and the like

metal salts of amino acids

p-styrenesulfonic acid

metal p-styrenesulfonate

2-methacryloyloxyethylsulfonic acids

metal 2-methacryloyloxethylsulfonates

3-methacryloyloxy-2-hydroxypropylsulonic acids

metal 3-methacryloyloxy-2-hydroxypropylsulfonates

2-acrylamido-2-methylpropanesulfonic acids

metal 2-acrylamido-2-methylpropanesulfonates

allylsulfonic acid

metal allylsulfonate and the like.

In one embodiment, the polyanionic components include anionic polysaccharides, other than cyclodextrins, which tend to exist in ionized forms at higher pH's, for example, pH's of about 7 or higher. The following are some examples of anionic polysaccharides which may be employed in accordance with this invention.

Polydextrose is a randomly bonded condensation polymer of dextrose which is only partially metabolized by mammals. The polymer can contain a minor amount of bound sorbitol, citric acid, and glucose.

Chondroitin sulfate also known as sodium chondroitin sulfate is a mucopolysaccharide found in every part of human tissue, specifically cartilage, bones, tendons, ligaments, and vascular walls. This polysaccharide has been extracted and purified from the cartilage of sharks.

Carrageenan is a linear polysaccharide having repeating galactose units and 3,6 anhydrogalactose units, both of which can be sulfated or nonsulfated, joined by alternating 1-3 and beta 1-4 glycosidic linkages. Carrageenan is a hydrocolloid which is heat extracted from several species of red seaweed and irish moss.

Maltodextrins are water soluble glucose polymers which are formed by the reaction of starch with an acid and/or enzymes in the presence of water.

Other polysaccharides found useful in the present invention are hydrophilic colloidal materials and include the natural gums such as gellan gum, alginate gums, i.e., the ammonium and alkali metal salts of alginic acid and mixtures thereof. In addition, chitosan, which is the common name for deacetylated chitin is useful. Chitin is a natural product comprising poly-(N-acetyl-D-glucosamine). Gellan gum is produced from the fermentation of pseudomonas elodea to yield an extracellular heteropolysaccharide. The alginates and chitosan are available as dry powders from Protan, Inc., Commack, N.Y. Gellan gum is available from the Kelco Division of Merk & Co., Inc., San Diego, Calif.

Generally, the alginates can be any of the water-soluble alginates including the alkali metal alginates, such as sodium, potassium, lithium, rubidium and cesium salts of alginic acid, as well as the ammonium salt, and the soluble alginates of an organic base such as mono-, di-, or tri-ethanolamine alginates, aniline alginates, and the like. Generally, about 0.2% to about 1% by weight and, preferably, about 0.5% to about 3.0% by weight of gellan, alginate or chitosan ionic polysaccharides, based upon the total weight of the composition, are used to obtain the gel compositions of the invention.

A particularly useful class of polyanionic component includes anionic cellulose derivatives. Anionic cellulose derivatives include metal carboxymethylcelluloses, metal carboxymethylhydroxyethylcelluloses and hydroxypropylmethylcelluloses and derivatives thereof.

The present polyanionic components often can exist in the unionized state, for example, in the solid state, in combination with a companion or counter ion, in particular a plurality of discrete cations equal in number to the number of discrete anionic charges so that the unionized polyanionic component is electrically neutral. For example, the present unionized polyanionic components may be present in the acid form and/or in combination with one or more metals. Since the polyanionic components are preferably ophthalmically acceptable, it is preferred that the metal associated with the unionized polyanionic component be ophthalmically acceptable in the concentrations used. Particularly useful metals include the alkali metals, for example, sodium and potassium, the alkaline earth metals, for example, calcium and magnesium, and mixtures thereof. Sodium is very useful to provide the counter ion in the unionized polyanionic component. Polyanionic components which, in the unionized states, are combined with cations other than H+and metal cations can be employed in the present invention.

In a preferred embodiment, the polyanionic polymers are cyclized. More preferably, the cyclized anionic polymers include less than ten monomer units. Even more preferably, the cyclized polyanionic polymers include less than six monomer units.

The amount of SEC in the present compositions is not of critical importance so long as solubility at the alpha-2-adrenergic agonist component is at least somewhat increased and is present in a biologically acceptable amount. Such amount should be effective to perform the desired function or functions in the present composition and/or after administration to the human or animal. In one embodiment, the amount of SEC, preferably the polyanionic component, is sufficient to complex at least in a major amount, and more preferably substantially all, of the TAC in the present composition. In one useful embodiment, the amount of polyanionic component in the present composition is in the range of about 0.1% to about 30% (w/v) or more of the composition. Preferably, the amount of polyanionic component is in the range of about 0.2% (w/v) to about 10% (w/v). More preferably, the amount of polyanionic component is in the range of about 0.2% (w/v) to about 0.6% (w/v). Even more preferably, the polyanionic component is carboxymethylcellulose and is present in the composition in the range of about 0.2% (w/v) to about 0.6% (w/v). A particularly useful concentration of carboxymethylcellulose in the present composition is about 0.5%.

In one embodiment, carboxymethylcellulose may help solubilize ionized TACs. In another embodiment, carboxymethylcellulose may help solubilize unionized TACs. In a preferred embodiment, the carboxylmethylcellulose help solubilize ionized Brimonidine tartrate. More preferably, the carboxylmethylcellulose helps solubilize unionized Brimonidine tartrate.

In one broad embodiment, the preservative components are selected so as to be effective and efficacious as preservatives in the present compositions, that is in the presence of SECs, and preferably have reduced toxicity and more preferably substantially no toxicity when the compositions are administered to a human or animal.

Preservatives which are commonly used in pharmaceutical compositions are often less effective when used in the presence of solubilizing agents. In certain instances, this reduced preservative efficacy can be compensated for by using increased amounts of the preservative. However, where sensitive or delicate body tissue is involved, this approach may not be available since the preservative itself may cause some adverse reaction or sensitivity in the human or animal, to whom the composition is administered.

Preferably, the present preservative components or components effective in aiding to preserve the compositions are effective in concentrations of less than about 1% (w/v) or about 0.8% (w/v) and may be 500 ppm (w/v) or less, for example, in the range of about 10 ppm (w/v) or less to about 200 ppm (w/v). Preservative components or components effective in aiding to preserve the compositions in accordance with the present invention preferably include, but are not limited to, those which form complexes with the polyanionic component to a lesser extent than does benzalkonium chloride.

Examples of the components effective in aiding to preserve the compositions, preferably the TACs therein, include, but are not limited to, oxidative preservative components, for example oxy-chloro components, peroxides, persalts, peracids, and the like, and mixtures thereof. Specific examples of oxy-chloro components useful as preservatives in accordance with the present invention include hypochlorite components, for example hypochlorites; chlorate components, for example chlorates; perchlorate components, for example perchlorates; and chlorite components. Examples of chlorite components include stabilized chlorine dioxide (SCD), metal chlorites, such as alkali metal and alkaline earth metal chlorites, and the like and mixtures therefor. Technical grade (or USP grade) sodium chlorite is a very useful preservative component. The exact chemical composition of many chlorite components, for example, SCD, is not completely understood. The manufacture or production of certain chlorite components is described in McNicholas U.S. Pat. No. 3,278,447, which is incorporated in its entirety herein by reference. Specific examples of useful SCD products include that sold under the trademark Dura Klor by Rio Linda Chemical Company, Inc., and that sold under the trademark Anthium Dioxide by International Dioxide, Inc. An especially useful SCD is a product sold under the trademark Purite.RTM. by Allergan, Inc. Other examples of oxidative preservative components includes peroxy components. For example, trace amounts of peroxy components stabilized with a hydrogen peroxide stabilizer, such as diethylene triamine penta(methylene phosphonic acid) or 1-hydroxyethylidene-1, 1-diphosphonic acid, may be utilized as a preservative for use in components designed to be used in the ocular environment. Also, virtually any peroxy component may be used so long as it is hydrolyzed in water to produce hydrogen peroxide. Examples of such sources of hydrogen peroxide, which provide an effective resultant amount of hydrogen peroxide, include sodium perborate decahydrate, sodium peroxide and urea peroxide. It has been found that peracetic acid, an organic peroxy compound, may not be stabilized utilizing the present system. See, for example, Martin et al U.S. Pat. No. 5,725,887, the disclosure of which is incorporated in its entirety herein by reference.

In a broad embodiment of the invention, additional preservatives other than oxidative preservative components may be included in the compositions. The choice of preservatives may depend on the route of administration. Preservatives suitable for compositions to be administered by one route may possess detrimental properties which preclude their administration by another route. For nasal and ophthalmic compositions, preferred preservatives include quaternary ammonium compounds, in particular the mixture of alkyl benzyl dimethyl ammonium compounds and the like known generically as "benzalkonium chloride." For compositions to be administered by inhalation, however, the preferred preservative is chlorbutol and the like. Other preservatives which may be used, especially for compositions to be administered rectally, include alkyl esters of p-hydroxybenzoic acid and the like and mixtures thereof, such as the mixture of methyl, ethyl, propyl and butyl esters which is sold under the trade name "Nipastat."

In another broad aspect of the present invention, compositions are provided which comprise a TAC, a preservative component in an effective amount to at least aid in preserving, preferably in an amount effective to preserve, the compositions and a liquid carrier component. Preferably, the preservative components include oxy-chloro components, such as compounds, ions, complexes and the like which (1) do not substantially or significantly detrimentally affect the TACs in the compositions or the patients to whom the compositions are administered, and (2) are substantially biologically acceptable and chemically stable. Such compositions in accordance with the present invention comprise a TAC, an oxy-chloro component, and a liquid carrier component, and preferably are substantially free of cyclodextrins.

The carrier components useful in the present invention are selected to be non-toxic and have no substantial detrimental effect on the present compositions, on the use of the compositions or on the human or animal to whom the compositions are administered. In one embodiment, the carrier component is a liquid carrier. In a preferred embodiment, the carrier component is a liquid aqueous carrier component. A particularly useful aqueous liquid carrier component is that derived from saline, for example, a conventional saline solution or a conventional buffered saline solution. The aqueous liquid carrier preferably has a pH in the range of about 6 to about 9 or about 10, more preferably about 6 to about 8, and still more preferably about 7.5. The liquid medium preferably has an ophthalmically acceptable tonicity level, for example, of at least about 200 mOsmol/kg, more preferably in the range of about 200 to about 400 mOsmol/kg. In an especially useful embodiment, the osmolality or tonicity of the carrier components substantially correspond to the tonicity of the fluids of the eye, in particular the human eye.

In one embodiment, the carrier components containing the TACs, SECs and preservatives may have viscosities of more than about 0.01 centipoise (cps) at 25^oC., preferably more than about 1 cps, even more preferably more than about 10 cps at 25^oC. In a preferred embodiment, the composition has a viscosity of about 50 cps at 25^o C. and comprises a conventional buffer saline solution, a carboxymethylcellulose and a Brimonidine tartrate.

In order to insure that the pH of the aqueous liquid carrier component, and thus the pH of the composition, is maintained within the desired range, the aqueous liquid carrier component may include at least one buffer component. Although any suitable buffer component may be employed, it is preferred to select such component so as not to produce a significant amount of chlorine dioxide or evolve significant amounts of gas, such as CO₂. It is preferred that the buffer component be inorganic. Alkali metal and alkaline earth metal buffer components are advantageously used in the present invention.

Any suitable ophthalmically acceptable tonicity component or components may be employed, provided that such component or components are compatible with the other ingredients of the liquid aqueous carrier component and do not have deleterious or toxic properties which could harm the human or animal to whom the present compositions are administered. Examples of useful tonicity components include sodium chloride, potassium chloride, mannitol, dextrose, glycerin, propylene glycol and mixtures thereof. In one embodiment, the tonicity component is selected from inorganic salts and mixtures thereof.

The present compositions may conveniently be presented as solutions or suspensions in aqueous liquids or non-aqueous liquids, or as oil-in-water or water-in-oil liquid emulsions. The present compositions may include one or more additional ingredients such as diluents, flavoring agents, surface active agents, thickeners, lubricants, and the like, for example, such additional ingredients which are conventionally employed in compositions of the same general type.

The present compositions in the form of aqueous suspensions may include excipients suitable for the manufacture of aqueous suspensions. Such excipients are suspending agents, for example, sodium carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose, sodium alginate, polyvinylpyrrolidone, gun tragacanth and gun acacia; dispersing or wetting agents may be a naturally occurring phosphatide, for example, lecithin, or condensation products of ethylene oxide with long chain aliphatic alcohols, for example, heptadecaethyleneoxycetanol, or condensation products of ethylene oxide with partial esters derived from fatty acids and a hexitol such as polyoxyethylene sorbitol mono-oleate, or condensation products of ethylene oxide with partial esters derived from fatty acids and hexitol anhydrides, for example, polyoxyethylene sorbitan mono-oleate, and the like and mixtures thereof. Such aqueous suspensions may also contain one or more coloring agents, one or more flavoring agents and one or more sweetening agents, such as sucrose, saccharin, and the like and mixtures thereof.

The present compositions in the form of oily suspensions may be formulated in a vegetable oil, for example, olive oil, sesame oil or coconut oil, or in a mineral oil such as liquid paraffin. Such suspensions may contain a thickening agent, for example beeswax, hard paraffin or cetyl alcohol. Sweetening agents, such as those set forth above, and flavoring agents may be added to provide a palatable oral preparation.

The present compositions may also be in the form of oil-in-water emulsions. The oily phase may be a vegetable oil, for example, olive oil or arachis oil, or a mineral oil, for example, liquid paraffin, and the like and mixtures thereof. Suitable emulsifying agents may be naturally-occurring gums, for example, gum acacia or gun tragacanth, naturally-occurring phosphatides, for example, soya bean lecithin, and esters or partial esters derived from fatty acids and hexitol anhydrides, for example, sorbitan mono-oleate, and condensation products of the said partial esters with ethylene oxide, for example, polyoxyethylene sorbitan mono-oleate. The emulsions may also contain sweetening and flavoring agents.

The present compositions in the form of syrups and elixirs may be formulated with sweetening agents, for example, as described elsewhere herein. Such formulations may also contain a demulcent, and flavoring and coloring agents.

The specific dose level for any particular human or animal depends upon a variety of factors including the activity of the active component employed, the age, body weight, general health, sex, diet, time of administration, route of administration, rate of excretion, drug combination and the severity of the particular condition undergoing therapy.

Claim 1 of 49 Claims

What is claimed is:

1. A composition comprising:

a therapeutically active component selected from the group consisting of alpha-2-adrenergic agonists and mixtures thereof, and being present in an amount effective to provide a desired therapeutic benefit to a patient to whom the composition is administered;

a solubility enhancing component, other than a cyclodextrin, in an amount effective to increase the solubility of the therapeutically active component in the composition relative to the solubility of an identical therapeutically active component in a similar composition without the solubility enhancing component;

an oxy-chloro component in an effective amount to at least aid in preserving the composition; and

a liquid carrier component.
 

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