PT - JOURNAL ARTICLE AU - Odette A. Fahmi AU - Sherri Boldt AU - Mary Kish AU - R. Scott Obach AU - Larry M. Tremaine TI - PREDICTION OF DRUG-DRUG INTERACTIONS FROM IN VITRO INDUCTION DATA AID - 10.1124/dmd.108.021907 DP - 2008 Sep 01 TA - Drug Metabolism and Disposition PG - 1971--1974 VI - 36 IP - 9 4099 - http://dmd.aspetjournals.org/content/36/9/1971.short 4100 - http://dmd.aspetjournals.org/content/36/9/1971.full SO - Drug Metab Dispos2008 Sep 01; 36 AB - Cytochrome P450 induction-mediated drug-drug interaction (DDI) is one of the major concerns in clinical practice and for the pharmaceutical industry. Previously, a novel approach [the relative induction score (RIS)] was developed using the Fa2N-4 immortalized human hepatocyte line and proposed as a tool for predicting magnitude of clinical DDIs caused by induction of CYP3A. The approach is based on combining in vitro induction parameters (EC50 and Emax) with the efficacious free plasma concentrations to calculate a relative induction score, which is correlated to the magnitude of clinical DDI for midazolam or ethinyl estradiol. To expand the applicability of the RIS model, we have measured induction caused by ten drugs in two different lots of human cryopreserved hepatocytes and correlated the data to clinical DDIs using the RIS. The results demonstrated that, as with Fa2N-4 hepatocytes, sigmoidal relationships can be derived between RIS and magnitude of induction of midazolam and ethinyl estradiol clearance in cryopreserved human hepatocytes. This study demonstrates the general applicability of the relative induction score approach using the human cryopreserved hepatocyte model to predict clinical DDI. The American Society for Pharmacology and Experimental Therapeutics