Bimatoprost A Review of its Use in Open-Angle Glaucoma and Ocular Hypertension

Bimatoprost (Lumigan (R)) is a synthetic prostamide that reduces intraocular pressure (IOP) by increasing the outflow of aqueous humour. In patients with open-angle glaucoma or ocular hypertension, long-term treatment (for up to 48 months) with once-daily bimatoprost 0.03% ophthalmic solution was more effective than timolol twice daily in providing a sustained and stable reduction in IOP. Bimatoprost 0.03% ophthalmic solution demonstrated efficacy similar to, or greater than, the prostaglandin analogues latanoprost and travoprost in reducing IOP and achieving target IOP levels. Switching to bimatoprost was as effective in maintaining diurnal IOP control as switching to a fixed combination of latanoprost/timolol (in patients with IOP levels controlled with a nonfixed combination of latanoprost plus timolol), and similarly, or more, effective in lowering IOP and providing overall diurnal IOP control than switching to a combination of dorzolamide/timolol (in patients with IOP inadequately controlled with other antiglaucoma agents including timolol). Treatment with bimatoprost was generally well tolerated, with conjunctival hyperaemia (mostly mild), growth of eyelashes and ocular pruritus being commonly reported. Other adverse events included increases in the pigmentation of the iris, perorbital areas and eyelashes. Pharmacological Properties Bimatoprost is a synthetic prostamide analogue (structurally related to prostaglandin F-2 alpha) that reduces IOP by increasing the outflow of aqueous humour through the trabecular meshwork (pressure-sensitive) and uveoscleral (pressure-insensitive) routes. The IOP-reducing effect of bimatoprost starts approximate to 4 hours after the first administration of this agent, with the maximum effect being reached within approximate to 8-12 hours. Bimatoprost provides a constant level of IOP control throughout a 24-hour period. Penetration of topically administered bimatoprost ophthalmic solution is via the sclera and cornea. After topical administration, systemic absorption of bimatoprost was minimal; peak blood concentrations of bimatoprost were reached rapidly (within 10 minutes) and then declined to below the lower limit of detection within 1.5 hours of administration. There was no accumulation of bimatoprost over time. The elimination half-life of intravenous bimatoprost was approximate to 45 minutes. Bimatoprost is excreted via the urine and faeces. Therapeutic Efficacy Treatment with topical bimatoprost 0.03% once daily for up to 48 months provided sustained reductions in IOP that were significantly greater than those with timolol 0.5% twice daily in patients with glaucoma or ocular hypertension, according to data from two large (n = 596 and 602), 12-month, phase III, randomized, double-blind trials and the extensions of these trials. Over the 48 months of treatment, reductions of IOP from baseline at 0800 and 1000 hours were approximate to 2-4 mmHg (35-100%) greater with bimatoprost than with timolol. Bimatoprost was more effective than timolol at maintaining overall IOP control throughout the day, and significantly more bimatoprost than timolol recipients achieved target IOP levels. In several large (n >100), investigator-blind, multicentre trials of up to 6 months' duration, once-daily bimatoprost 0.03% demonstrated similar, or greater, efficacy than once-daily administration of the prostaglandin analogues latanoprost 0.005% or travoprost 0.004% in lowering IOP and maintaining a stable diurnal IOP in patients with glaucoma or ocular hypertension. Patients (inadequately controlled on latanoprost) who switched to bimatoprost achieved significantly greater reductions in IOP than those remaining on latanoprost or switching to travoprost, according to data from two 3-month, randomized, investigator-blind studies. Switching to bimatoprost was as effective in maintaining diurnal IOP control as switching to a fixed combination of latanoprost 0.005%/timolol 0.5% in patients with IOP levels controlled with a nonfixed combination of latanoprost plus timolol, according to data from a 3-month, randomized, double-blind trial in patients with glaucoma. Bimatoprost once daily demonstrated similar or greater efficacy than dorzolamide/timolol twice daily in lowering IOP and in providing overall diurnal control in patients with ocular hypertension and glaucoma, according to data from randomized trials in patients with IOP inadequately controlled with antiglaucoma agents including topical timolol. Pharmacoeconomic Considerations Cost-effectiveness analyses of bimatoprost treatment in patients with glaucoma or ocular hypertension conducted from a US healthcare provider perspective demonstrated that bimatoprost was associated with lower costs per treatment success than latanoprost, timolol or timolol/dorzolamide across a range of IOP targets. In all US analyses, bimatoprost was the dominant (more effective and less costly) strategy compared with latanoprost. Data from cost-effectiveness analyses conducted from a European healthcare provider perspective also demonstrated the dominance of bimatoprost over latanoprost for most of the countries assessed. One European analysis also demonstrated that a strategy of first-line timolol therapy with add-on bimatoprost was the dominant strategy compared with latanoprost (as first-line therapy or as add-on therapy to timolol) in the UK, Spain, Germany and Italy. As well as being subject to the usual limitations associated with economic models, other potential limitations associated with these analyses included the use of selected IOP data and the lack of the inclusion of costs associated with conjunctival hyperaemia or other adverse effects of therapy. Tolerability Once-daily treatment with bimatoprost 0.03% for up to 48 months was well tolerated in patients with glaucoma or ocular hypertension. The most commonly reported adverse events were conjunctival hyperaemia (mostly mild) and eyelash growth, occurring in 45% and 43% of bimatoprost recipients during the first year of treatment, according to data from two large, phase III trials. Only 3% of recipients of bimatoprost once daily withdrew due to ocular hyperaemia during the first year of treatment. The incidence of both of these adverse events decreased with continued treatment over a 48-month period. Ocular pruritus was another commonly reported adverse event (15%) during the first year of treatment; however, the incidence of new reports of ocular pruritus was minimal during the second year of treatment, with no new cases being reported in subsequent years. Other ocular adverse events, including ocular dryness, visual disturbance and ocular burning, occurred in up to 10% of bimatoprost recipients. The incidence of iris pigmentation reported in bimatoprost recipients in the 12-month, phase III trials was low (1.5%), and there were no new reports of iris pigmentation changes with continued bimatoprost treatment of up to 48 months.