Evaluation of circadian control of intraocular pressure after a single drop of bimatoprost 0.03% or travoprost 0.004%

Comparison of human ocular distribution of bimatoprost and latanoprost

PURPOSE

This study investigated the ocular distribution of bimatoprost, latanoprost, and their acid hydrolysis products in the aqueous humor, cornea, sclera, iris, and ciliary body of patients treated with a single topical dose of 0.03% bimatoprost or 0.005% latanoprost for understanding concentration-activity relationships.

METHODS

Thirty-one patients undergoing enucleation for an intraocular tumor not affecting the anterior part of the globe were randomized to treatment with bimatoprost or latanoprost at 1, 3, 6 or 12 h prior to surgery. Concentrations of bimatoprost, bimatoprost acid, latanoprost, and latanoprost acid in the human aqueous and ocular tissues were measured using liquid chromatography tandem mass spectrometry.

RESULTS

Following topical administration, intact bimatoprost was distributed in human eyes with a rank order of cornea/sclera >iris/ciliary body >aqueous humor. Bimatoprost acid was also detected in these tissues, where its low levels in the cornea relative to that of latanoprost acid indicated that bimatoprost hydrolysis was limited. Latanoprost behaved as a prodrug that entered eyes predominantly via the corneal route. Levels of latanoprost acid were distributed as cornea >>aqueous humor>iris>sclera>ciliary body.

CONCLUSIONS

Our study provided experimental evidence that levels of bimatoprost in relevant ocular tissues, and not only aqueous humor, are needed to understand the mechanisms by which bimatoprost lowers intraocular pressure (IOP) in human subjects. The data suggest that bimatoprost reached the target tissues favoring the conjunctival/scleral absorption route. Findings of intact bimatoprost in the target ciliary body indicated its direct involvement in reducing IOP. However, bimatoprost acid may have only a limited contribution on the basis that bimatoprost has greater/similar IOP-lowering efficacy than latanoprost, yet bimatoprost acid levels were a fraction of latanoprost acid levels in the aqueous humor and cornea and only sporadically detectable in the ciliary body. In this report, human ocular tissues were examined concurrently with aqueous humor for the in vivo distribution of bimatoprost, bimatoprost acid, latanoprost, and latanoprost acid.

Bimatoprost: a review of its use in open-angle glaucoma and ocular hypertension

Bimatoprost (Lumigan) 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.

Commercially available prostaglandin analogs for the reduction of intraocular pressure: similarities and differences

Over the last 12 years, the pharmacological management of glaucoma and ocular hypertension has significantly changed with the introduction of the prostaglandin analogs, specifically, latanoprost, bimatoprost, and travoprost. Their ability to effectively reduce intraocular pressure with once-per-day dosing, their comparable ocular tolerability with timolol, and their general lack of systemic side effects have made them the mainstay of pharmacological therapy for glaucoma and ocular hypertension in most parts of the world. A review of their pharmacology reveals that they are all prodrugs that are converted to their respective free acids within the eye to activate the prostanoid FP receptor and to reduce intraocular pressure by enhancing the uveoscleral and the trabecular meshwork outflow pathways. A review of numerous prospective, randomized comparative studies indicates that no clinically significant differences exist among these agents regarding their ability to lower intraocular pressure.