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# Guidance on Drug Metabolite Safety Testing
- URL: https://www.fdaweb.com/guidance-on-drug-metabolite-safety-testing/
- Published: 2016-11-22T12:00:00.000Z
- Updated: 2026-09-14T21:49:42.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5137403

FDA has posted a [guidance](http://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/UCM079266.pdf?ref=fdaweb.com) on “Safety Testing of Drug Metabolites” that provides recommendations to industry on when and how to identify and characterize drug metabolites whose nonclinical toxicity needs to be evaluated. “The safety of drug metabolites may need to be determined in nonclinical studies because these metabolites are either identified only in humans or are present at disproportionately higher levels in humans than in any of the animal species used during standard nonclinical toxicology testing,” the document says. The guidance applies to small molecule nonbiologic drug products, but does not apply to some cancer therapies where a risk-benefit assessment is considered, the agency says. It supersedes the guidance of the same name published 2/2008.