Topical Beta-blockade with Intrinsic Sympathomimetic Activity offers no Advantage for the Respiratory and Cardiovascular Function of Elderly People

摘要

Topical therapy with beta-antagonists, such as timolol, may cause unrecognized impairment of respiratory and cardiovascular function in elderly people. Beta-antagonists with intrinsic sympathomimetic or cardioselective properties, such as carteolol or betaxolol, may cause less impairment. In a randomized, double-masked study of glaucoma patients, over 60 years of age, without history of bronchospasm and who were using timolol (0.5%), 60 patients were allocated to betaxolol (0.5%) or carteolol (2%) or continued timolol (0.5%) treatment. Spirometry, pulse and blood pressure were measured on enrolment and after 4 weeks. In the timolol and carteolol groups there were no significant changes in mean spirometric values. Changing to betaxolol improved mean peak flow (PF) by 9.1%, from 310 to 341 l/min (p < 0.05) and forced expiratory volume in 1 second (FEV_1) by 9.4%, from 1.74 to 1.861 (p < 0.05). Differences in the changes in PF and FEV_1 between betaxolol and timolol as well as betaxolol and carteolol groups were statistically significant (p < 0.05). Twenty-one per cent of those allocated to betaxolol showed clinically significant improvement in FEV_1. There was no change in pulse or blood pressure when carteolol was substituted for timolol but an increase of 10 beats per minute (p < 0.05) in mean resting pulse in the betaxolol group. Therapy with cardioselective beta-blockers may offer significant advantages in respiratory function for elderly people with glaucoma over non-selective drugs, even if they have sympathomimetic activity.