In Vitro Metabolism- and Transporter-Mediated Drug-Drug Interaction Studies, and Clinical Drug Interaction Studies-Study Design, Data Analysis, and Clinical Implications; Draft Guidances for Industry; Availability

The Food and Drug Administration (FDA or Agency) is announcing the availability of two draft guidances for industry entitled ``In Vitro Metabolism- and Transporter-Mediated Drug-Drug Interaction Studies'' (in vitro DDI guidance) and ``Clinical Drug Interaction Studies--Study Design, Data Analysis, and Clinical Implications'' (clinical DDI guidance). These two draft guidances will update and replace the revised draft guidance for industry entitled ``Drug Interaction Studies--Study Design, Data Analysis, Implications for Dosing, and Labeling Recommendations'' issued February 21, 2012 (2012 draft guidance). These draft guidances are intended to assist drug developers in the planning and evaluation of drug-drug interaction (DDI) potential during drug development. In particular, the in vitro DDI guidance focuses on in vitro experimental approaches for evaluating metabolizing enzyme- and transporter-based drug interaction potential and how to extrapolate in vitro data to decide on the need for clinical DDI studies. The clinical DDI guidance focuses on clinical studies that evaluate the potential for DDIs, which alter a drug's pharmacokinetics by modulating the effects of drug metabolizing enzymes and transporters, and advises sponsors on the timing and design of the clinical studies, interpretation of the results, and options for managing DDIs in patients. Together, these two draft guidances describe a systematic, risk-based approach to the assessment of DDIs.