TOPICAL OPHTHALMIC BETA-BLOCKERS - A COMPARATIVE REVIEW

Topically administered beta blockers are the preferred medical therapy for glaucoma. These agents reduce intraocular pressure (IOP), thereby preventing damage to the optic nerve and the subsequent loss of visio n. Timolol, betaxolol, levobunolol, metipranolol, and carteolol are th e topical beta blockers available in the U.S. They have similar IOP-lo wering efficacy, but differ in other pharmacological properties. Topic ally administered beta blockers are generally well tolerated. They und ergo systemic absorption, however, and can adversely affect cardiovasc ular and bronchopulmonary function in patients with existing diseases such as heart failure, sinus bradycardia, chronic obstructive airways disease, or asthma. Betaxolol, which is beta1-selective, and carteolol , which has intrinsic sympathomimetic activity (ISA), may have systemi c tolerability profiles superior to the traditional nonselective, non- ISA beta blockers. These hypotheses require confirmation in controlled clinical trials. Local adverse effects associated with beta blockers include stinging, burning, red eye, itching, tearing and loss of corne al sensitivity. Stinging upon instillation is a particularly frequent finding with betaxolol (up to 30% to 40% of patients). Preliminary evi dence suggests that carteolol has the best local tolerability profile of these drugs.