title: Studies on N-demethylation of methamphetamine by liver microsomes of guinea-pigs and rats: the role of flavin-containing mono-oxygenase and cytochrome P-450 systems.
abstract: Relative participation of flavin-containing mono-oxygenase and cytochrome P-450 systems in N-hydroxylation of and formaldehyde release from methamphetamine were studied in vitro using liver microsomes of guinea-pigs and rats. In guinea pigs, only methimazole, an inhibitor of flavin-containing mono-oxygenase, significantly suppressed the above reactions. Formaldehyde release from methamphetamine was significantly inhibited not only by methimazole but also by inhibitors of the cytochrome P-450 system in liver microsomes from rats, but not guinea-pigs. Pretreatment of guinea-pigs with phenobarbital and 3-methylcholanthrene did not enhance the metabolism of methamphetamine. Pretreatment of rats with phenobarbital but not 3-methylcholanthrene increased slightly the N-demethylation of methamphetamine by liver microsomes. The results indicate that a marked species difference exists in the enzymes concerned with N-demethylation of methamphetamine. N-Oxidation predominates in guinea-pigs, whereas in rats, N-oxidation and C-oxidation of the methyl group participate equally as the initial reaction of the N-demethylation pathway.
mesh_terms: D000818:Animals; D002849:Chromatography, Gas; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D003640:Dealkylation; D006168:Guinea Pigs; D006900:Hydroxylation; D066298:In Vitro Techniques; D008297:Male; D008694:Methamphetamine / Q000378:metabolism*; D008862:Microsomes, Liver / Q000201:enzymology*; D010105:Oxygenases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013045:Species Specificity
chemical_list: D065607:Cytochrome P-450 Enzyme Inhibitors; D008694:Methamphetamine; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases; C020066:dimethylaniline monooxygenase (N-oxide forming)