The FDA has updated final guidance on safety testing for drug metabolites to conform to the ICH’s latest standards on toxicity detection and testing.

In a revision to final guidance from February 2008, the FDA now directs sponsors to the ICH’s 2010 guidelines on nonclinical safety studies for advice on the duration of a general toxicity study with direct dosing of metabolites.

The ICH guideline, dubbed M3 (R2) Nonclinical Safety Studies for the Conduct of Human Clinical Trials and Marketing Authorization for Pharmaceuticals, was adopted two years after the FDA finalized its guidance on assessing the safety of drug metabolites. It’s intended to improve the harmonization of the nonclinical safety studies to support the various stages of clinical development among EU, Japanese, and the U.S. regulators.