New FDA guidance available for in vitro drug interaction studies

The U.S. Food and Drug Administration (FDA) published “In Vitro Drug Interaction Studies – Cytochrome P450 Enzyme- and Transporter-mediated Drug Interactions Guidance for Industry” in January. The guidance is available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/vitro-drug-interaction-studies-cytochrome-p450-enzyme-and-transporter-mediated-drug-interactions.

This guidance is intended to help drug developers plan and evaluate studies to determine the drug-drug interaction (DDI) potential of an investigational drug product. It focuses on in vitro approaches to evaluate the interaction potential between investigational drugs with cytochrome P450 enzymes and transporters, as well as how in vitro results can inform future clinical DDI studies. The appendices of this guidance include factors to consider when choosing in vitro experimental systems, key issues regarding in vitro experimental conditions, and more detailed explanations regarding model-based DDI prediction strategies.