Avoiding unsuspected respiratory side-effects of topical timolol with cardioselective or sympathomimetic agents.

Topical timolol given for the treatment or chronic simple glaucoma may cause unrecognised bronchospasm among elderly people. We recruited 80 patients aged over 60 years, who were without a history of airways disease and already used timolol, into a randomised crossover study comparing the effects on spirometry and exercise tolerance of changing to betaxolol or dipivefrine therapy. Results showed an increase of 13% and 8% in mean peak flow rate and forced expiratory volume in 1 s (FEV1), respectively, when using betaxolol; and of 14% and 11% when using dipivefrine. There was also improved exercise tolerance with both agents. More than a quarter of the patients showed at least a 15% improvement in FEV1 when changed from timolol. Analysis of enrolment symptoms and response to nebulised salbutamol failed to produce a method of identifying these patients. Timolol may impair respiratory function and exercise tolerance of elderly patients even if they have no history of reversible airways disease.