A comparative analysis of select P450 enzymes in uninduced and PB/BNF-induced hamster and rat liver S9.

The assessment of potentially carcinogenic N-nitrosamine impurities in drugs has become crucial for the pharmaceutical industry to ensure public safety. The in vitro Ames test, which uses rat or hamster liver S9 for metabolic activation, is an important component of regulatory test batteries for assessing mutagenicity and has been the traditional method for assessing the potential mutagenicity of chemicals, including N-nitrosamines. This test, however, has shown inconsistencies with some N-nitrosamines, raising concerns about the liver S9's ability to activate N-nitrosamines to their proximate mutagens.