Drug interaction generally refers to a modification of the expected drug response in the patient as a result of exposure of the patient to another drug or substance. Some unintentional drug interactions produce adverse reactions in the patient, whereas some drug interactions may be intentional, to provide an improved therapeutic response or to decrease adverse drug effects. Drug interactions may include drug-drug interactions, food-drug interactions, or chemical-drug interactions, such as the interaction of a drug with alcohol or tobacco. A listing of food interactions is given in . A drug-laboratory test interaction pertains to an alteration in a diagnostic laboratory test result because of the drug.
This topic describes: Pharmacokinetics of Drug Interaction: Pharmacokinetic drug interactions, Inhibition and Induction of Drug metabolism and Inhibition of Biliary Excretion.