Effects on exercise tachycardia during forty-eight hours of a series of doses of atenolol, sotalol, and metoprolol

Publisher Website
Google Scholar
Abstract
Beta adrenoceptor blockers differ mainly in their plasma elimination half-lives (t1/2). Drugs with longer t1/2 may have a longer duration of effect on exercise tachycardia. Several factors may influence the duration of action of .beta. blockers; the contribution of plasma elimination t1/2 and dose was investigated by comparing the effects on an exercise tachycardia in healthy subjects of placebo 25, 50, 100 and 200 mg of atenolol and of sotalol, and 50, 100, 200 and 400 mg metoprolol. Subjects exercised before and at 2, 3, 6, 8, 24, 33 and 48 h after oral doses of each drug. Plasma samples for measurement of drug concentration were drawn before each exercise period. Twenty-four hours after 50, 100, and 200 mg atenolol and 50, 100, 200 and 400 mg sotalol there were reductions in an exercise tochycardia; at this time reductions were greater after the larger dosages. The plasma elimination t1/2 of atenolol were between 7.2 .+-. 1.2 and 9.1 .+-. 1.6 h and for sotalol were 9.2 .+-. 0.7 and 10.1 .+-. 1.0 h. Although 50, 100 and 200 mg metoprolol induced the same reductions in an exercise tachycardia 2 h after drug as 25, 50 and 100 mg atenolol and 200 mg sotalol, these doses were without effect at 24 h. Metoprolol 400 mg reduced exercise tachycardia at 24 h but the effect was less than that of the 3 largest doses of atenolol and sotalol. The plasma elimination t1/2 for metoprolol was between 3.6 .+-. 0.6 and 5.0 .+-. 1.8 h. Duration of cardiac .beta. blocking activity of atenolol, sotalol and metoprolol evidently is determined by the elimination t1/2 and dose.

This publication has 2 references indexed in Scilit: