title: Measurement of mephenytoin (3-methyl-5-ethyl-5-phenylhydantoin) and its demethylated metabolite by selective ion monitoring.
abstract: Mephenytoin (3-methyl-5-ethyl-5-phenylhydantoin) and its demethylated metabolite Nirvanol (5-ethyl-5-phenylhydantoin) were measured by a selective ion monitoring technique. This method was used in the analysis of both compounds in plasma from a patient receiving 50 mg and 400 mg of mephenytoin in single oral doses. Both compounds were extracted from plasma and ethylated prior to analysis by electron-impact mass spectrometry. Alkylation, using ethyl iodide in 2-butanone, occurred in the N-1 and N-3 positions of the hydantoin ring when concentrated KOH was added to the reaction mixture. The lower limits of quantitation for mephenytoin and Nirvanol were 10 ng/ml and 50 ng/ml, respectively, and were found to be reproducible within 8% upon repeated quantification.
mesh_terms: D004827:Epilepsy / Q000188:drug therapy / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006801:Humans; D006827:Hydantoins / Q000097:blood*; D008617:Mephenytoin / Q000097:blood* / Q000627:therapeutic use; D013997:Time Factors
chemical_list: D006827:Hydantoins; D008617:Mephenytoin