The potential systemic effect of topically applied β-blockers in glaucoma therapy

Although topical beta-blockers are generally tolerated, they can produce significant systemic side effects. The systemic side effects of nonselective beta-blockers (eg, timolol, carteolol) are primarily related to the cardiovascular (beta 1-adrenergic) and respiratory (beta 2-adrenergic) systems. Carteolol has intrinsic sympathomimetic activity, which theoretically reduces the risk of adverse effects through beta blockade. It has been reported that topical timolol and carteolol unfavorably alter the lipid profile and that the effects of carteolol are less pronounced than those of timolol. Topical beta-blockers are associated with systemic events, not only acting by themselves, but also interacting with other drugs (eg, quinidine) administered orally or intravenously. To reduce systemic absorption and adverse effects, new preparations of beta-blockers, such as timolol gellan, have been developed. We should always bear in mind the potential systemic effects of topically applied beta-blockers in glaucoma therapy.