Thebaine metabolites in the urine of rhesus monkeys

The metabolic fate of thebaine in rhesus monkeys was investigated. Using thin layer chromatography, more than four metabolites were detected in the urine of monkeys given thebaine (8 mg/kg, s.c.). Two of the metabolites isolated by high performance liquid chromatography were not consistent with those reported previously. With the use of gas chromatography-mass spectrometry, the structures were identified as oripavine (3-O-demethylthebaine) and nororipavine (3-O,N-di-demethylthebaine) from the mass spectra of their trimethylsilyl and propionyl derivatives. Further experiments with liver microsomes from rhesus monkeys showed that, in addition to these metabolites, northebaine was also formed from thebaine in the presence of NADPH.