FDA Releases Guidance on Safety Testing for Drug Metabolites

Manufacturers should attempt to identify differences in drug metabolism between animals used in nonclinical safety assessments and humans as early as possible during the drug development process to ensure timely assessment of potential safety issues, the FDA recommends in a draft guidance.

The draft guidance, titled "Safety Testing of Drug Metabolites," offers methods to identify quantitative and qualitative differences in metabolic profiles across animal species to assess safety in humans during risk assessment.

As a general guideline, the FDA says metabolites in human plasma that account for more than 10 percent of drug-related material should be considered during the safety assessment. The agency cautions that some metabolites present at less than 10 percent should also be tested, depending on the situation.

The draft guidance includes a decision-tree flow chart to help manufacturers determine at which point in the development process the studies should be conducted.

To view the guidance, go to ()a href="http://www.fda.gov/OHRMS/DOCKETS/98fr/2005d-0203-gdl0001.pdf" target="_blank">http://www.fda.gov/OHRMS/DOCKETS/98fr/2005d-0203-gdl0001.pdf.