Bronchial reactivity in healthy individuals undergoing long-term topical treatment with beta-blockers

Objective: To assess the impact of long-term treatment with topical timolol on bronchial reactivity in healthy individuals. Methods: Twenty-one otherwise healthy individuals with high-pressure primary open-angle glaucoma were enrolled in a randomized controlled clinical trial. Eleven patients underwent 3 years of topical 0.5% timolol treatment followed by a 1-year washout period; 10 patients underwent primary argon laser trabeculoplasty. Functional variables and bronchial reactivity (forced expiratory volume in I second and metacholine challenge test results) were assessed in both groups at enrollment and after 3 and 4 years of follow-up. Results: After 3 years, a measurable response to metacholine challenge was recorded in 6 of 11 otherwise symptom-free individuals treated with 0.5% timolol twice daily. A detectable response to metacholine challenge was still present in half of these individuals (3 of 6) when further washed out for 1 year from the topical beta-blocker. No significant variation in bronchial reactivity was measured in the laser-treated group during 4 years of follow-up. Conclusions: Healthy individuals who undergo longterm topical application of a nonselective beta-blocker (0.5% timolol) can develop a subclinical increase in bronchial reactivity. This phenomenon may not be completely reversible on withdrawal of the beta-blocker.