Abstract
1. The rates of N-oxide formation from pyridine, nicotinamide and isonicotinamide by rat liver microsomes and by cultured rat hepatocytes have been quantified using a simple h.p.l.c. system.
2. Hepatocytes produce hetero-aromatic N-oxides for at least 5 h, making them a useful system to study the N-oxidation of pyridines.