Article: PDF OnlyThe cytochrome P450 system and adverse drug reactionsShenfield, Gillian; Gross, AnnetteAuthor Information Department of Clinical Pharmacology, Royal North Shore Hospital, St Leonards NSW 2065, Australia. Email: [email protected] Adverse Drug Reaction Bulletin: February 1999 - Volume 194 - Issue 1 - p 739-742 Buy Abstract The cytochrome P450 superfamily plays an important role in drug metabolism. Many environmental and genetic factors regulating the activity of individual enzymes, as well as their drug substrates, have been described. In several cases the cytochrome P450 enzymes are genetically polymorphic, resulting in phenotypically distinct poor and extensive metabolizers for some drugs. Poor metabolizers are susceptible to concentration-related adverse drug reactions, whilst extensive metabolizers are susceptible to drug interactions; inhibitory interactions may result in toxicity due to increased plasma concentrations. Altered drug metabolism is an important cause of adverse drug reactions. © 1999 Lippincott Williams & Wilkins, Inc.