PT - JOURNAL ARTICLE AU - R K Lynn AU - J E Bauer AU - W P Gordon AU - R G Smith AU - D Griffin AU - R M Thompson AU - R Jenkins AU - N Gerber TI - Characterization of mephenytoin metabolites in human urine by gas chromatography and mass spectrometry. DP - 1979 May 01 TA - Drug Metabolism and Disposition PG - 138--144 VI - 7 IP - 3 4099 - http://dmd.aspetjournals.org/content/7/3/138.short 4100 - http://dmd.aspetjournals.org/content/7/3/138.full SO - Drug Metab Dispos1979 May 01; 7 AB - Metabolites of mephenytoin (5-ethyl-3-methyl-5-phenylhydantoin) were characterized in human urine following chromatography on XAD-2 resin, permethylation, and combined gas chromatography and mass spectrometry. Four glucuronide metabolites previously unidentified in man were characterized as their permethylated derivatives by chemical-ionization and electron-impact mass spectrometry. These metabolites included 5-ethyl-5-(hydroxyphenyl)-3-methylhydantoin O-glucuronide; 5-hydroxyethyl-3-methyl-5-phenyl-hydantoin O-glucuronide; 5-ethyl-5-(hydroxymethoxyphenyl)-3-methylhydantoin O-glucuronide; and a metabolite tentatively identified as 5-ethyl-5-phenylhydantoin N3-glucuronide in which both N-demethylation and glucuronide conjugation of the hydantoin ring have occurred. Mephenytoin, N-demethylmephenytoin, 5-ethyl-5-(hydroxyphenyl)-3-methylhydantoin, and 5-ethyl-5-(hydroxymethoxyphenyl)-3-methylhydantoin were characterized in extracts of enzymatically hydrolyzed urine.