Metabolic N-oxidation of metronidazole

Metronidazole when treated at the N-3 nitrogen with a mixture of hydrogen peroxide and acetic acid, or liver homogenate preparations, yields the N-3 oxide as identified by thin-layer chromatographic analysis on silica gel G, RF 0.62 in ethanol-chloroform-ammonia (50:49:1), by chemical reduction with sulphur dioxide, and by ultra-violet spectrophotometry and nuclear magnetic resonance spectroscopy. Incubation of metronidazole at 37 degrees C with rat liver 10,000g supernatant fortified with cofactors gave a product with identical chromatographic and UV spectral data suggesting that metronidazole like other tertiary amine drugs undergoes microsomal N-oxidation.