Effects of Timolol and of Timolol with Tamarind Seed Polysaccharide on Intraocular Pressure in Rabbits

Tamarind seed polysaccharide (TS-P) has high viscosity and mucoadhesive properties which make it a suitable candidate for addition to ophthalmic solutions of β-adrenergic blockers to increase the residence time on the cornea. The effect of an ophthalmic preparation containing timolol and TS-P on intraocular pressure (IOP) was evaluated in rabbits. Ocular administration of 0.5% timolol or 0.5% timolol with 1 and 2% TS-P, into the conjunctival sac had no effect on normal IOP, but significantly reduced betamethasone-induced ocular hypertension, over 20 days. The effect lasted up to 12 h after treatment with timolol + TS-P, and was still present on day 20 of treatment. Timolol in association with TS-P had a prolonged duration of action and is suitable for ocular administration in cases of elevated IOP.