Ocular effects in normal rabbits of topically applied labetalol: a combined alpha- and beta-adrenergic antagonist

The ocular effects in rabbits of topically applied labetalol hydrochloride, a new alpha- and beta-adrenergic receptor blocking agent, were studied. A dose-related reduction in intraocular pressure (IOP) followed treatment with 0.01% to 1% solutions. Labetalol at a 1% concentration had no effect on pupil diameter. The same dose blocked an increase in IOP after water loading but did not significantly alter the coefficient of aqueous outflow facility. Mydriasis induced by phenylephrine hydrochloride was competitively inhibited.