Identification of new urinary metabolites of famprofazone in humans.

Urinary metabolites of famprofazone following oral administration in humans were identified by gas chromatography-mass spectrometry with electron impact-ionization and comparison with the spectra and retention times of authentic standards. The metabolites were determined following selective derivatization with N-methyl-bis-trifluoroacetamide (MBTFA) and N-methyl-N-trimethyl silyl trifluoroacetamide (MSTFA). Famprofazone was rapidly and extensively metabolized by N-dealkylation, beta-hydroxylation, and p-hydroxylation. The major metabolite, representing approximately 15% of the dose, was methamphetamine. The other metabolites, which were present in minor amounts, were amphetamine, norephedrine, norpseudoephedrine, ephedrine, pseudoephedrine, p-hydroxyamphetamine, p-hydroxymethamphetamine, and p-hydroxydemethyl famprofazone.