Antiglaucoma —bimatoprost
Glaucoma is a serious disease of the eye, in which excessively high pressure within the eye leads to loss of vision. Chronic simple, or open angle, glaucoma is the most common form. The rise in pressure is gradual and usually painless, with the impairment to the vision progressing slowly. Acute, or angle closure, glaucoma involves a rapid rise in intraocular pressure, and is less common. It is caused by the sudden closing of the angle between the cornea and the iris, blocking the drainage of aqueous humour from the eye, and is accompanied by pain and visual blurring.
The ultimate cure is surgery to drain aqueous humour from the eye, but drugs can often be used instead. Acetazolamide, for example, blocks the production of aqueous humour; other drugs improve the flow of intraocular fluid out of the eye.
Prostaglandin analogues have been used as a topical treatment for some years, as they increase the outflow of the aqueous humour. However, existing drugs cause side-effects such as irritation, headache and excessive blood collection in the conjunctiva. In a search for prostaglandin analogues that are effective against glaucoma but are free from the side-effects, Allergan discovered the molecule AGN-192024, now referred to as bimatoprost.
In a randomised double blind placebo controlled trial in 25 healthy volunteers, intraocular pressure reduced by 20% after three days of treatment with bimatoprost compared with placebo.1 A parallel study against timolol in 60 patients with open angle glaucoma or ocular hypertension showed significant reductions in intraocular pressure, and higher reductions in the bimatoprost group.2
Two ongoing 6-month multi-centre randomised double blind trials showed that a once daily dosing of 0.03% bimatoprost was the optimum regime. The drug was well tolerated.3
Bimatoprost has been approved by the FDA for open angle glaucoma and ocular hypertension, and has been submitted for approval in the EU.