FIELD OF THE INVENTION

The present invention relates to a novel ophthalmic solution of bimatoprost or its pharmaceutically acceptable salts.

BACKGROUND OF THE INVENTION

Bimatoprost is available at 0.03% w/v concentration with 0.05 mg/ml of benzalkonium chloride, under the brand name of Latisse® by Allergan. This product is used to treat hypotrichosis of the eyelashes by increasing their growth including length, thickness and darkness. The solution contained 0.05 mg/ml of benzalkonium chloride as preservative. Later, ophthalmic solution of bimatoprost at 0.03% w/v concentration and 0.05 mg/ml of benzalkonium chloride, for reducing elevated intra-ocular pressure in patients with open angle glaucoma or ocular hypertension was made available by Allergan, under the brand name Lumigan® 0.03%. Allergan subsequently improved this by reducing the bimatoprost concentration to 0.01% w/v (Lumigan® 0.01%), but contained very high concentration of benzalkonium chloride i.e. 0.2 mg/ml which is as high as four times the concentration present in Latisse® and Lumigan® 0.03%.

The present inventors have found an ophthalmic solution of bimatoprost that show high ocular bioavailability without use of benzalkonium chloride. In fact the present inventors have found ophthalmic solutions that have improved ocular bioavailability as compared to the marketed preparation that uses benzalkonium chloride 0.2 mg/ml as a penetration enhancer and preservative. The inventors obtained the result with the use of acylated amino acid in combination with a biguanide compound preservative.

SUMMARY OF THE INVENTION

The present invention provides an ophthalmic solution comprising—(i) bimatoprost or its pharmaceutically acceptable salt in an amount ranging from about 0.005% to 0.015% weight by volume;(ii) a biguanide compound present in an amount ranging from about 0.003% to 0.05% weight by volume;(iii) an acylated amino acid present in an amount ranging from about 0.01% to 0.1% weight by volume;(iv) pharmaceutically acceptable excipients and(v) purified water;

