Active drug metabolites in drug development

Active drug metabolites discovered during the course of drug development constitute a subset of the larger issue of metabolic drug interactions, but still demand unique consideration from both an efficacy and a safety point of view. Improved technology has allowed better identification and quantification of metabolites, raising new issues to be addressed during the course of drug development. Several new molecular identities recently entering the marketplace have active metabolites, and many more are (or have been) in development. The MIST (Metabolites in Safety Testing) committee of PhRMA (Pharmaceutical Research and Manufacturers of America) has prepared a position paper (in press) on the subject, which has been widely discussed (with and by regulatory authorities) over the past three years.