ANTIGLAUCOMA COMPOSITIONS CONTAINING COMBINATIONS OF SYMPATHOMIMETIC AGENTS AND BETA-1 SELECTIVE BETA-BLOCKERS

Abstract: Ophthalmic pharmaceutical compositions useful in controlling elevated intraocular pressure associated with glaucoma and other ophthalmic conditions are described. A method of controlling elevated intraocular pressure with those compositions is also described. The compositions contain a sympathomimetic agent having beta-2 agonist activity to enhance the outflow of aqueous humor, and a beta-1 selective beta-blocker to reduce production of aqueous humor, whereby therapeutic control of intraocular pressure is achieved.

Description: ANTI6LAUC0MA COMPOSITIONS CONTAINING COMBINATIONS OF SYMPATHOMIMETIC AGENTS AND BETA-1 SELECTIVE BETA-BLOCKERS Background of the Invention 1. Field of the Invention The present invention relates to the field of ophthalmology. More particularly, the invention relates to the treatment of glaucoma and associated elevations of intraocular pressure, and to the treatment of ocular hypertension associated with other diseases or conditions. The invention is directed to providing topical, ophthalmic, pharmaceutical compositions which include, as principal active ingredients, combina¬ tions of one or more beta-1 selective beta-blockers (e.g., betaxolol) and one or more sympathomi etic agents having beta-2 agonist activity (e.g., epinephrine) . 2. Discussion of Related Art The underlying causes of glaucoma are not fully understood. The symptomatology of this disease includes elevated pressure levels within the eye. These pressure elevations may be caused by either over pro¬ duction of fluid within the eye, or inadequate outflow of fluid from the eye. The intraocular fluid is referred to as "aqueous humor." The internal pressure of the eye associated with the amount of fluid inside the eye is referred to as "intraocular pressure" or "IOP." Although the causes of« glaucoma and associated elevations of intraocular pres¬ sure are not fully understood, the prognosis of untreated or inade¬ quately treated glaucoma is known to include very serious ocular manifestations, namely blindness or significant loss of vision. Thus, there is a continuing need for therapies which control the elevated intraocular pressure associated with glaucoma. A significant number of glaucoma patients are required to administer more than one drug in order to achieve therapeutic control of their intraocular pressure. In other words, a single drug does not provide adequate control of intraocular pressure in these patients. The drugs currently utilized in the treatment of glaucoma include miotics (e.g., pilocarpine, carbachol , and acetylcholinesterase inhibitors), .sympathomimetics (e.g., epinephrine and dipivalylepinephrine), beta-blockers (e.g., betaxolol, levobunolol and timolol) and carbonic anhydrase inhibitors (e.g., acetazolamide, methazolamide and ethoxzolamide). Miotics and sympathomimetics are believed to lower intraocular pressure by increasing the outflow of aqueous humor, while beta-blockers and carbonic anhydrase inhibitors are believed to lower intraocular pressure by decreasing the formation of aqueous humor. All four types of drugs have potential side effects. Miotics, such as pilocarpine, can cause blurring of vision and other visual side effects which may either decrease patient compliance or require termination of miotic drug therapy. Carbonic anhydrase inhibi¬ tors can also cause serious side effects which affect patient compli¬ ance and/or necessitate withdrawal of the drug therapy. At least one beta-blocker, timolol, has increasingly become associated with serious pulmonary side effects attributable to its effect on beta-2 receptors in pulmonary tissue. In addition to these side effects, a therapy regimen which includes the use of two or more pharmaceutical composi¬ tions containing drugs selected from two or more of the above-cited classes requires the patient to apply the compositions to the affected eye(s) in separate, spaced dosages, several times per day. Patient compliance with such complicated dosage regimens can be very poor, particularly in elderly patients. Since the majority of glaucoma patients are elderly, this patient compliance problem is significant. In light of the foregoing circumstances, it is clear that a need exists for new, more potent antiglaucoma compositions which avoid or reduce the above-cited side effects and enhance patient compliance. The present invention is directed to the provision of such compositions. Summary of the Invention The present invention is directed to the provision of antiglaucoma compositions which comprise a combination of one or more sympathomimetic agents having beta-2 agonist activity and one or more beta-1 selective beta-blockers. The invention is also directed to methods of controlling elevated intraocular pressure utilizing those compositions. Sympathomimetic agents, which for purposes of the present specification are defined as compounds having beta-2 agonist activity, are known to lower intraocular pressure. Epinephrine and dipavalylepinephrine have been used for that purpose for many years. Sympathomimetic agents are believed to reduce intraocular pressure by increasing the outflow of aqueous humor through the trabecular meshwork of the eye. Although the mechanism is not entirely clear, it is believed that these agents promote the outflow of aqueous humor by binding with beta-2 receptors in the trabecular meshwork. Beta-blockers, such as timolol and betaxolol, are also known to lower intraocular pressure, and have been utilized for that purpose for several years. The biological mechanism by which beta-blockers lower intraocular pressure is not entirely clear. It is believed that these - compounds control intraocular pressure by decreasing the production of aqueous humor in the ciliary processes of the eye. As mentioned above, two or more different types of drugs are sometimes required to achieve therapeutic control of intraocular pres¬ sure. The use of a drug which increases outflow of aqueous humor with a drug which reduces aqueous humor formation has the advantage of reducing intraocular pressure via two different mechanisms. Since two different mechanisms are involved, it might be expected that the reduc¬ tion in intraocular pressure would be additive; that is, the total reduction in intraocular pressure achieved with the two drugs is the sum of the reductions achieved with each type of drug. However, previous studies have indicated that the concurrent use of epinephrine, a sympathomimetic compound, and timolol, a beta-blocker, does not result in such an additive reduction in intraocular pressure. Rather, the results of these studies suggest that timolol somehow interferes with the action of epinephrine. See Allen et al., "Additive Effect of Betaxolol and Epinephrine in Primary Open-Angle Glaucoma," Archives of Ophthalmology, Vol. 104, pages 1178-1184 (1986), and the references cited therein. The results of the study by Allen et al . also indicate that the concurrent use of a composition containing betaxolol and a composition containing epinephrine does result in an additive reduction of intraocular pressure. The present invention is directed to topical, ophthalmic, pharmaceutical compositions containing combinations of certain beta- blocking agents and sympathomimetic agents, which compositions are surprisingly effective in lowering intraocular pressure. The beta- blockers utilized in the present invention are beta-1 selective. This means that the compounds bind predominantly with beta-1 receptors rather than beta-2 receptors. While applicant does not wish to be bound by any theory, it is believed that the beta-1 selective beta- blockers utilized in the present invention do not interfere significantly with the outflow-enhancing activity of sympathomimetic agents, because those beta-blockers bind predominantly with beta-1 receptors rather than beta-2 receptors, and therefore do not interfere or compete with the binding of sympathomimetic agents with the beta-2 - receptors of the trabecular meshwork. Whatever the mechanism, it is clear that compositions containing a combination of a beta-1 selective beta-blocker, such as betaxolol, and a sympathomimetic agent, such as epinephrine, reduce intraocular pressure to an extent greater than that achievable by utilizing either agent alone. Detailed Description of the Invention The antiglaucoma compositions of the present invention comprise a combination of a therapeutically effective amount of one or more sympathomimetic agents and a therapeutically effective amount of one or more beta-1 selective beta-blockers. The ratio of the sympathomimetic component to the beta-1 selective beta-blocker component may vary con¬ siderably depending on the relative potency of the specific components utilized and other factors, such as the degree of intraocular pressure reduction desired and the nature of the condition being treated. With respect to the latter factor, it is conceivable that increasing aqueous humor outflow in some patients will have a more profound effect on intraocular pressure than reducing aqueous humor production, or vice versa. The ratio of the components employed is therefore left to the discretion of skilled clinicians. The ratio on a percent by weight concentration basis will typically be in the range of about 0.1:10 to 10:0.1 sympathomimetic agent:beta-l selective beta-blocker. The sympathomimetic agents which can be employed in the compositions of the present invention include all pharmaceutically acceptable compounds capable of enhancing the outflow of aqueous humor. In view of the apparent mechanism of action of the sympathomimetics, any pharmaceutically acceptable compound having beta-2 agonist activity may be utilized as the sympathomimetic component of the present compositions. Preferred sympathomimetic compounds include epinephrine, dipavalylepinephrine, norepinephrine, isoproterenol and the pivaloyloxy and phenylacetyloxy ester derivatives of epinephrine and norepinephrine described in U.S. Patents Nos. 3,809,714; 3,839,584; and 4,085,270. The entire contents of those patents are hereby incorporated in the present specification by reference. Epinephrine and dipavalyl¬ epinephrine are particularly preferred. The antiglaucoma compositions ■ of the present invention will typically contain one or more sympathomimetic agents in an amount of about 0.02 to 2.0 percent by weight (wt. %) . The beta-1 selective beta-blockers which may be utilized in the present invention include all pharmaceutically acceptable compounds which are capable of reducing the production of aqueous humor and have a predominant affinity for beta-1 receptors rather than beta-2 recep¬ tors. The most preferred beta-1 selective beta-blocker is betaxolol. Other preferred beta-1 selective beta-blockers include acebutolol, adi olol, atenolol, befunolol, bisoprolol, carteolol, celiprolol, cetamolol, cicloprolol, draquinolol, epanolol, esmolol, etoprolol, SKF 95018, salcardolol, tienoxolol, tolamolol, and xa oterol. All of the foregoing compounds are known. The antiglaucoma compositions of the present invention will typically contain one or more beta-1 selec¬ tive beta-blockers in an amount of about 0.01 to 3.0 percent by weight (wt. %). In addition to the above-described principal active ingredients, the antiglaucoma compositions of the present invention may further comprise various for ulatory ingredients, such as antimicrobial preservatives and tonicity agents. Examples of suitable antimicrobial preservatives include: benzalkonium chloride, thimerosal, chloro- butanol , methyl paraben, propyl paraben, phenylethyl alcohol, edetate disodium, sorbic acid, ONAMER M and other agents equally well known to those skilled in the art. Such preservatives, if utilized, will typically be employed in an amount of from about 0.001% to 1.0% by weight (wt. %) . Examples of suitable agents which may be utilized to adjust the tonicity or osmolality of the formulations include sodium chloride, potassium chloride, mannitol, dextrose glycerine and propy- lene glycol. Such agents, if utilized, will be employed in an amount of about 0.1% to 10.0% by weight (wt. %) . As will be appreciated by those skilled in the art, the compositions may be formulated in various dosage forms suitable for topical ophthalmic delivery, including solutions, suspensions, emul¬ sions, gels, and erodible solid ocular inserts. The compositions are preferably aqueous, and have a pH in the range of 3.5 to 8.0 and an osmolality in the range of 280 to 320 millimoles per liter (mm/1). The following example further illustrates the antiglaucoma compositions of the present invention. Example The following formulation is typical of aqueous ophthalmic solutions of the present invention. Ingredient Amount (wt. %) Dipavalylepinephrine 0.1 Betaxolol 0.5 Benzalkonium Chloride 0.01 Edetate Sodium 0.05 HCl and/or NaOH QS pH 7.4 Purified Water QS 100 The present invention is also directed to methods of treating and controlling ocular hypertension associated with glaucoma and other ophthalmic diseases and abnormalities. The methods comprise topical application of a therapeutically effective amount of a composition according to the present invention to the affected eye(s) of the patient. The frequency and amount of the dosage will be determined by the clinician- based on various clinical factors. The methods will typically comprise topical application of one to two drops (or an equivalent amount of a solid or semisolid dosage form) to the affected eye one to two times per day.

Claims: What Is Claimed Is: 1. A topical-ophthalmic composition useful in controlling intraocular pressure, comprising a combination of an amount of a beta-2 agonist and an amount of a beta-1 selective beta-blocker effective to control intraocular pressure; and a pharmaceutically acceptable vehicle. 2. A topical ophthalmic composition according to Claim 1, wherein the beta-2 agonist is selected from epinephrine, norepinephrine, isoproterenol, and pivaloyloxy and phenylacetyloxy esters of epinephrine and norepinephrine, and the beta-1 selective beta-blocker is selected from acebutolol, adimolol, atenolol, befunolol, betaxolol, bisoprolol, carteolol, celiprolol, cetamolol, cicloprolol, draquinolol, epanolol, esmolol, metoprolol, SKF 95018, salcardolol, tienoxolol, tolamolol, and xamoterol. 3. A topical ophthalmic composition according to Claim 1, wherein the beta-2 agonist comprises epinephrine and the beta-1 selective beta- blocker comprises betaxolol. 4. A topical ophthalmic composition according to Claim 1, wherein the beta-2 agonist comprises dipavalylepinephrine and the beta-1 selective beta-blocker comprises betaxolol. 5. A method of controlling intraocular pressure which comprises applying a therapeutically effective amount of a composition according to Claim 1 tqpically to the affected eye.

Inventors: DE SANTIS LOUIS M, DE SANTIS, LOUIS, M.
Applicants: ALCON LAB INC, ALCON LABORATORIES, INC.
Application year: 1989
Main classification: A61K31
IPC codes: A61K31, A61K45, A61P27