Plasma verapamil levels and exercise performance

Publisher Website
Google Scholar
Abstract
A study in 10 patients with stable, exercise-related angina under a double-blind, placebo-controlled protocol correlated plasma verapamil levels after single oral doses of 120 and 240 mg and exercise performance. Plasma verapamil levels peaked at 2 h in 7 patients and 4 h in 3 patients and declined thereafter, with a mean plasma t1/2 [half-life] of 3.22 and 4.54 h after the 120- and 240-mg dose. Despite the relatively short t1/2, total exercise duration and time to onset of angina and S-T segment depression were longer than placebo values for 4 h after the 120-mg dose and for 8 h after the 240-mg dose. Percentage increase in treadmill time and log of plasma verapamil levels correlated. All patients with plasma levels above 100 ng/ml had at least a 50% increase in exercise duration. Measurement of plasma verapamil levels are useful in patients who fail to respond to a dose of verapamil. If the level is below 100 ng/ml, increasing the dose of verapamil may improve response.