Autonomic regulation involved in the ocular hypotensive action of (β-adrenergic blocking agents

Abstract

Abstract The effects of racemic propranolol and some related drugs on the intraocular pressure (IOP) were studied after topical application in rabbits. These drugs produced a significant reduction in IOP with the following order of potency: (−)-propranolol > timolol > (±)-propranolol > sotalol > (+)-propranolol > pranolium. Pretreatment of rabbit eyes with atropine significantly antagonized the ocular hypotensive action of (±)-propranolol, timolol and pranolium. Both (±)-propranolol and timolol produced a significant increase in pupil diameter in the presence of a submydriatic dose of atropine. The activities of monoamine oxidase and carbonic anhydrase were unaffected by (±)-propranolol, timolol and pranolium in-vitro. It is concluded from the results that both cholinergic and adrenergic mechanisms may be involved in the ocular hypotensive effects of the drugs.