Disposition of methadone in methadone maintenance.
Six detoxified opiate addicts housed in a closed metabolic ward received methadone in stepwise increasing doses of 10, 20, 40, and 80 mg/day during 1 month. Four were given 14C-methadone at the lowest dose and again at the highest dose. Of the subjects receiving radiomethadone, 2 excreted the major part of the radioactivity in urine and 2 about equally in urine and feces. In addition to methadone, 7 metabolites were isolated and identified in urine and 3 metabolites in feces. About 75% of the urinary and fecal radioactive metabolites were unconjugated. Urinary excretion of methadone and its major N-monomethylated metabolite accounted for 17% to 57% of the given dose. The ratio of metabolite to parent drug increased in 5 of 6 subjects, and the urinary recovery of unchanged methadone decreased during the period. The results indicate that enhanced demethylation of methadone may occur during oral administration to man.
D000328:Adult; D002250:Carbon Radioisotopes; D002849:Chromatography, Gas; D003640:Dealkylation; D005243:Feces / Q000032:analysis; D005260:Female; D006556:Heroin Dependence / Q000534:rehabilitation*; D006801:Humans; D006900:Hydroxylation; D008297:Male; D008691:Methadone / Q000378:metabolism* / Q000627:therapeutic use / Q000652:urine; D010087:Oxides / Q000652:urine; D013997:Time Factors
D002250:Carbon Radioisotopes; D010087:Oxides; D008691:Methadone