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# Drug-Drug Interaction Guidances Out
- URL: https://www.fdaweb.com/drug-drug-interaction-guidances-out/
- Published: 2017-10-25T12:00:00.000Z
- Updated: 2026-09-14T22:58:15.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5139956

FDA has released two draft guidances that together describe a systematic, risk-based approach to evaluating drug-drug interactions (DDIs) and communicating the results of DDI studies. The first [guidance](http://www.fda.gov/downloads/Drsugs/GuidanceComplianceRegulatoryInformation/Guidances/UCM292362.pdf?ref=fdaweb.com), *Clinical Drug Interaction Studies—Study Design, Data Analysis, and Clinical Implications*, is to help sponsors of investigational NDAs and applicants of NDAs evaluate drug-drug interactions during drug development and communicate the results and recommendations from DDI studies. It focuses on the conduct of clinical studies to evaluate the DDI potential of an investigational drug, including **(1)** the timing and design of the clinical studies; **(2)** the interpretation of the study results; and **(3)** the options for managing DDI in patients.

The related [guidance](http://www.fda.gov/downloads/Drsugs/GuidanceComplianceRegulatoryInformation/Guidances/UCM581965.pdf?ref=fdaweb.com), *In Vitro Drug Metabolism- and Transporter-Mediated Drug-Drug Interaction Studies*, focuses on *in vitro* experimental approaches to evaluate the interaction between investigational drugs that involves metabolizing enzymes and/or transporters. It also discusses how *in vitro* results can inform future clinical DDI studies. The guidance’s appendices include considerations when choosing *in vitro* experimental systems, key issues regarding *in vitro* experimental conditions, and more detailed explanations regarding model-based DDI prediction strategies.