Species differences in the disposition and metabolism of 1-methyl-3-(3-pyridyl)-5-(2-hydroxy-methylphenyl)-1H-1,2,4-triazole, a potential sedative-hypnotic compound

1H nuclear magnetic resonance study of metronidazole metabolism by perfused rat liver

High-resolution 1H nuclear magnetic resonance (NMR) spectroscopy at 300 MHz has been used to monitor the metabolism of metronidazole by the perfused rat liver. Samples of perfusate removed at various times during the perfusion show resonances from metronidazole and its major metabolites, as well as those from organic metabolites released from the liver. The major metabolite of metronidazole is shown to be its glucuronide conjugate. Metronidazole metabolism and glucuronide production are both stimulated in livers from rats pretreated with phenobarbitone.

Influence of species, sex and drug pretreatment on the metabolism of metyrapone

The metabolism of metyrapone was investigated in three mammalian and four non-mammalian species, and keto reduction was found to be the major metabolic route (except in the cat). Toad, lizard and tortoise did not form metyrapone N-oxides. Rat and cat formed both isomeric N-oxides of metyrapone, whereas rabbit and pigeon have a limited capacity to form only the N-oxide II and N-oxide I, respectively. There were marked sex differences in both keto reduction and N-oxidation in the rat. Anthracene did not affect metyrapone N-oxides formation in the male rat; however phenobarbitone and pregnenolone significantly induced N-oxide II formation, whereas ethanol induced both isomeric N-oxides formation. Cimetidine, a known cytochrome P-450 inhibitor, inhibited the N-oxide II formation but with an enhanced N-oxide I formation.