title: Plasma verapamil levels and exercise performance.
abstract: Our 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 hr in seven patients and 4 hr in three patients and declined thereafter, with a mean plasma t1/2 of 3.22 and 4.54 hr after the 120- and 240-mg dose. Despite the relatively short t1/2s, total exercise duration and time to onset of angina and S-T segment depression were longer than placebo values for 4 hr after the 120-mg dose and for 8 hr 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. Thus 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.
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000787:Angina Pectoris / Q000188:drug therapy; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004562:Electrocardiography; D006207:Half-Life; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D005082:Physical Exertion; D011897:Random Allocation; D014700:Verapamil / Q000097:blood* / Q000378:metabolism / Q000627:therapeutic use
chemical_list: D014700:Verapamil