Pulmonary Effects of Topical Timolol

Timolol, a beta-adrenergic blocking agent, recently became available for the treatment of glaucoma. We report the occurrence of acute bronchospasm in a previously asymptomatic asthmatic patient following topical use of timolol. Therapy with the drug was discontinued, and four weeks later the patient was challenged with two drops of 0.5% timolol. A 25% decrease in forced expiratory volume at one second (FEV1) was demonstrated at one hour. The fall in FEV1 was even greater (47%) when the patient was rechallenged with four drops. We emphasize the need to avoid topical beta-adrenergic blocking agents in asthmatic patients.