Topical bimatoprost - A review of its use in open-angle glaucoma and ocular hypertension

Bimatoprost, a synthetic prostamide analogue, is a new ocular hypotensive agent indicated for the second-line treatment of open-angle glaucoma and ocular hypertension. The drug is formulated as a 0.03% ophthalmic solution. Bimatoprost lowers intraocular pressure (IOP) by increasing aqueous humour outflow. When applied topically once daily in patients with ocular hypertension or glaucoma, bimatoprost 0.03% significantly reduced IOP. Mean IOP was reduced by approximately 7.5 to 9.2mm Hg 12 hours after drug administration in randomised clinical trials. The reduction in IOP was maintained throughout the 24-hour dosage interval. Once-daily treatment with bimatoprost 0.03% was found to be significantly more effective than timolol 0.5% (administered twice daily as an ophthalmic solution or once daily as a gel-forming solution) in randomised comparative trials in patients with ocular hypertension and glaucoma. Furthermore, after I to 6 months' treatment, the percentage of patients reaching a target IOP of less than or equal to17mm Hg was significantly greater in the bimatoprost-treated groups than in those receiving timolol. Bimatoprost 0.03% ophthalmic solution was found to be at least as effective as topical latanoprost 0.005% administered once daily in two clinical trials. Reductions in IOP 16 and 20 hours postdose were greater in patients treated with bimatoprost, indicating superior control of IOP at timepoints throughout the dosage interval. In patients refractory to beta-blocker therapy, treatment with bimatoprost 0.03% produced greater reductions in diurnal IOP measurements than combination therapy with topical dorzolamide 2%/timolol 0.5%; approximately twice as many bimatoprost 0.03% recipients achieved an IOP of less than or equal to16mm Hg. The most commonly reported adverse effect during clinical trials of once-daily bimatoprost 0.03% was conjunctival hyperaemia which occurred in 42 to 46% of patients treated. However, most cases were mild and only I to 4% of patients withdrew from treatment as a result. Overall withdrawal rates as a result of adverse events during clinical trials ranged from 2.6 to 7%. Bimatoprost has been reported to cause changes in the pigmentation of the periorbital skin, eyelashes and iris, and increase eyelash growth. The long-term consequences of these effects are unknown. Cardiopulmonary adverse effects, which have been associated with the use of beta-blockers such as timolol, were not reported in clinical trials of bimatoprost. Thus, in clinical trials of up to 1-year duration, bimatoprost 0.03% has been found to be effective in significantly lowering IOP and is generally well tolerated. It provides an alternative treatment option for patients in whom beta-blockers are contraindicated. Furthermore, bimatoprost provides an effective second-line treatment option in patients who do not achieve target IOP with other topical ocular hypotensive agents, or who experience unacceptable adverse effects. Wider clinical use of this drug will establish the place of bimatoprost in the treatment of open-angle glaucoma and ocular hypertension.