TY - JOUR T1 - Evidence for an arene oxide-NIH shift pathway in the metabolic conversion of phenytoin to 5-(4-hydroxyphenyl)-5-phenylhydantoin in the rat and in man. JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 667 LP - 671 VL - 10 IS - 6 AU - M Claesen AU - M A Moustafa AU - J Adline AU - D Vandervorst AU - J H Poupaert Y1 - 1982/11/01 UR - http://dmd.aspetjournals.org/content/10/6/667.abstract N2 - To determine whether the hydroxylation of 5,5-diphenylhydantoin (DPH) to 5-(4-hydroxyphenyl)-5-phenylhydantoin (p-HPPH) occurs by an arene oxide-NIH shift process, racemic 5-(4-deuteriophenyl)-5-phenylhydantoin (p-2H-DPH) was subjected to in vivo metabolic experiments in the rat and in man. After enzymatic hydrolysis of the urine, para-hydroxylated metabolites were separated by HPLC. Deuterium retention in the isolated metabolites determined by gas chromatography-mass spectrometry, was 68-72%. The results are interpreted as the predominance of an arene oxide-NIH shift pathway in those two metabolic systems. Induction of rats with phenobarbital or 3-methylcholanthrene showed no effect on the value of deuterium retention. ER -