Selectivity of Bevantolol Hydrochloride, a β‐Adrenoceptor Antagonist, in Asthmatic Patients

Abstract

Bevantolol hydrochloride, a new β-adrenoceptor antagonist, has been shown to be cardioselective in animals. To evaluate its selectivity in humans, a double-blind, crossover study was conducted in 8 asthmatics. Following a single oral dose of placebo, bevantolol 75 or 150 mg or propranolol hydrochloride 40 mg, forced expiratory volume in 1 second (FEV₁), heart rate, blood pressure and skeletal muscle tremor were measured before and after 4 increasing intravenous doses of terbutaline sulfate to establish terbutaline dose-reponse curves. The FEV₁ decreased after all active treatments. During terbutaline infusions there was an increase in FEV₁ after both bevantolol doses and placebo. The terbutaline dose-response curve after bevantolol shifted to the right, however. After propranolol, there was no increase in FEV₁ during terbutaline stimulation. Heart rate and skeletal muscle tremor showed a similar pattern during the experiment. In dosages that have previously been shown to produce at least the same degree of blockade of exercise-induced tachycardia, bevantolol has less influence on terbutaline-induced bronchodilation, heart rate increase and skeletal muscle tremor than did propranolol. Thus bevantolol has relative β₁-adrenoceptor antagonist selectivity. Drawing upon the results of a previous study in the same patients, we believe bevantolol, atenolol and metoprolol have similar β₁-selectivity.