Drug glucuronidation in clinical psychopharmacology

Glucuronidation is a phase II metabolic process and one of the most common pathways in the formation of hydrophilic drug metabolites. At least 33 fami lies of uridine diphosphate-glucuronosyltransferases have been identified i n vitro, and specific nomenclature similar to that used to classify the cyt ochrome (CYP) P450 system has been established. The UGT1 and UGT2 subfamili es represent the most important of these enzymes in human drug metabolism. Factors affecting glucuronidation include the following: cigarette smoking, obesity, age, and gender. In addition, several drugs have been found in vi tro to be substrates, inhibitors, or inducers of UGT enzymes. Induction or inhibition of both UGT and CYP isoforms may occur simultaneously. Some impo rtant drug interactions involving glucuronidation have been documented and others can be postulated. This review summarizes the relevant literature pe rtaining to drug glucuronidation and its implications for clinical psychoph armacology.