Bimatoprost: A Novel Antiglaucoma Agent

Abstract

The aim of glaucoma therapy is to preserve vision by reducing intraocular pressure (IOP). Following recent National Eye Institute sponsored studies, it is becoming increasingly apparent that every mmHg of extra IOP lowering counts. Bimatoprost is the newest and most effective addition to the physician's armamentarium of ocular hypotensive drugs. Direct clinical comparisons have demonstrated that it is more efficacious than the prostaglandin (PG) FP receptor agonist prodrugs, latanoprost and travoprost, as well as a beta-adrenoceptor antagonist, timolol, alone or in fixed combination with the carbonic anhydrase inhibitor, dorzolamide. Moreover, patients that are refractory to latanoprost therapy may be successfully treated with bimatoprost. Such evidence provides support, at the clinical level, for the contention that bimatoprost is pharmacologically distinct from PG FP receptor agonist prodrugs. Bimatoprost is a structural analog of PGF2alpha-ethanolamide (prostamide F2alpha), which is formed from the endocannabinoid anandamide by a biosynthetic pathway involving cyclooxygenase-2 (COX-2). Their pharmacology is remarkably similar, such that bimatoprost may be regarded as a prostamide mimetic. The target receptor for bimatoprost and the prostamides appears unique and unrelated to PG- and endocannabinoid-sensitive receptors. Extensive ocular distribution/metabolism studies in non-human primates demonstrate that bimatoprost is not a prodrug, it remains essentially intact. Its profound ocular hypotensive effects may, therefore, be attributed to its prostamide-mimetic properties.

A Comparative Study on the Safety and Efficacy of Topical Bimatoprost With Timolol Maleate in Glaucoma Patients

“…Bimatoprost is the most recommended first line drug of choice for the cases of POAG, because each 1 mmHg IOP reduction decreases the risk of glaucoma progression by 10% and bimatoprost is more effective than other medications in reducing IOP. (6,10,16) Wider use of this drug will establish the place of Bimatoprost in treatment of primary open angle glaucoma and ocular hypertension.…”

“…(16) The only limitation for its use is regarding its cost. The topical bimatoprost preparations are more expensive when compared to the topical Timolol maleate.…”

“…And this may be due to minimal enzymatic hydrolysis of Bimatoprost in the ocular tissues acting directly as an intact molecule. (9,15,16) The most commonly reported side effects of Bimatoprost is conjunctival hyperaemia (i.e. ocular surface redness), which is observed in 12% cases.…”

“…ocular surface redness), which is observed in 12% cases. (16,17) which is only a cosmetic phenomenon.…”

The Role of Preservative-free Therapies in the Treatment of Glaucoma

“…19 Each of the prostaglandins has a different binding profile from the FP and EP receptors and as a result, has differing effects on blood vessels, blood flow and hyperaemia. [20][21][22] Consequently, individual patients show varying responses to the range of prostaglandins that are available and changing these drugs can have an effect on efficacy and/or tolerability.…”