Effect of exercise on renal clearance of atenolol

The effect of exercise on plasma atenolol was evaluated using a two-phase complete crossover study in 12 healthy volunteers. In one phase, the volunteers were subjected to physical exertion on a treadmill; in the other phase, they remained in a sitting or standing position. Following a single 100-mg atenolol dose, frequent blood samples and a complete urine collection were obtained over 24 hr. Plasma and urine atenolol levels were assayed by high-pressure liquid chromatography. Plasma atenolol was significantly (p less than 0.05) higher during the exercise phase of the study, and this result was associated with approximately an 8% decrease in the renal clearance of the drug, probably due to decreased renal blood flow during exercise.