EFFECT OF EXERCISE ON DISPOSITION AND PHARMACOKINETICS OF DRUGS

The effect of various drugs on exercise in man and animal has been reported but there are very few reports which evaluate the effect of exercise on the disposition and pharmacokinetics of drugs. Exercise in general decreases the absorption after oral administration and increases absorption after intramuscular and subcutaneous administration. Exercise decreases the distribution and excretion of flow‐limited drugs and increases the distribution and excretion for capacity‐limited drugs. Treadmill or running wheel, but not swimming exercise diminishes or elevates the Phase I metabolism and glucuronidation. The effect of exercise on drug metabolism may be substrate specific, suggesting alterations in isozymes of Cyt P‐450. Exercise also decreases glutathione concentration. Effect of exercise on drug disposition is also related to the other factors including temperature, pH, drug permeability, and barometric pressure; the most critical factor, however, appears to be altered blood flow which occurs with exercise. There is a wide inter‐ and intraindividual variation in the metabolism and pharmacokinetics of drugs due to exercise. It remains to be determined what factors play a major role in drug disposition as a consequence of exercise. Exercise influences the amount of drug reaching the receptor site, which has significant affect on pharmacodynamic activity. This aspect of pharmacology has great implications in therapeutics particularly for drugs which have a low margin of safety. Copyright © 1990 Wiley‐Liss, Inc.