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

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 (FEV 1 ), 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 FEV 1 decreased after all active treatments. During terbutaline infusions there was an increase in FEV 1 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 FEV 1 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 β 1 ‐adrenoceptor antagonist selectivity. Drawing upon the results of a previous study in the same patients, we believe bevantolol, atenolol and metoprolol have similar β 1 ‐selectivity.