Beta-adrenergic blocking agents are widely used to treat disorders of cardiac rhythm and rate, angina, and hypertension. Propranolol is the most widely used beta-adrenergic blocking agent in this country. Because of its nonselective beta-adrenergic blocking effect, propranolol may be associated with significant bronchoconstriction in asthmatic subjects and in some patients with chronic obstructive pulmonary disease. Since tolamolol, a new beta-adrenergic blocking agent, has cardioselectivity in animals, we studied asthmatic subjects for six hours on three separate days in a double-blind crossover comparison of oral therapy with 40 mg of propranolol, its beta-adrenergic blocking equivalent dose of tolamolol (50 mg), and a high dose of tolamolol (100 mg). All three dosages had equipotent effects on heart rate and systolic pressure. The 50-mg dose of tolamolol had no effect on pulmonary function over six hours; however, both propranolol (40 mg) and the 100-mg dose of tolamolol had equivalent deleterious effects on airway resistance and on rates of expiratory flow. We conclude that the cardioselectivity of tolamolol is dose-limited but is present at the dosage of 50 mg, which is equivalent to the usual antiarrhythmic beta-adrenergic blocking dose of propranolol (40 mg).

Aerosol terbutaline is an effective bronchodilator agent with at least a seven-hour duration of action in patients with reversible obstruction of the airways. Inhalation of up to 1.5 mg of this drug is not associated with significant alterations of pulse rate and blood pressure. Although a dose-related improvement of specific airway conductance was demonstrated 30 minutes after administration of the drug, no such effect was observed in measurements of the forced expiratory volume in one second.