Drug Interactions: Effects of Drugs and Chemicals on Drug Metabolism

Abstract

Summary The rate of metabolism of drugs by certain hepatic enzymes can be decreased or increased. These changes in drug metabolism can occur rapidly or be delayed in onset, and can be of short duration or be maintained for several months. There is no good way to predict what will cause these changes in drug metabolism. Among chemicals affecting these hepatic enzymes, there is no one active structure. Whether such changes in drug biotransformation will affect the action of a subsequently administered drug depends upon the importance of metabolism to that drug's action. Three points deserve emphasis: (1) changes in drug metabolism can result from the administration of any of a variety of widely used chemicals and drugs; (2) an abnormal rate of drug metabolism can be associated with unusual drug reactions; and (3) these phenomena can occur in humans.