Systemic effects of topical ophthalmic β-adrenoceptor antagonists

Topical ophthalmic beta-adrenoceptor antagonists (beta-blockers) are generally recognized as the treatment of choice in glaucoma management due to favourable efficacy, safety and tolerability. Despite topical ocular administration, beta-blockers are systemically absorbed, in relatively small amounts, through the nasolacrimal drainage system and can adversely affect cardiovascular and pulmonary function. While cardioselective beta-blockers, such as betaxolol, possibly confer an advantage with respect to clinical safety through their receptor affinity, systemic effects are also influenced by other pharmacological factors, including the rate and extent of systemic absorption and the extent of plasma protein binding. These factors are reviewed to distinguish the various ophthalmic beta-blockers and to explain the observed clinical differences in the safety profiles of these medications.