The caffeine test

: The inhibition of oxidative drug metabolism is a major cause of clinically significant drug interactions. Among the possible modalities for exploring the enzyme inhibiting potential of drugs, the caffeine test is a valuable addition to the antipyrine test in man. Indeed, microsomal enzymes explored by the caffeine test differ from those attainable by the antipyrine test. After a short overview of caffeine pharmacokinetics, the features of the caffeine test are tentatively described. The results of published studies indicate the usefulness of this simple test for detecting those new drugs endowed with an enzyme inhibiting potential.