title: Sensitive method for the determination of phenytoin in plasma, and phenytoin and 5-(4-hydroxyphenyl)-5-phenylhydantoin in urine by high-performance liquid chromatography.
abstract: An isocratic high-performance liquid chromatographic method is described for the quantitative analysis of phenytoin (PHT) in plasma and both phenytoin and its main metabolite, 5-(4-hydroxyphenyl)-5-phenylhydantoin (p-HPPH) in urine. Following ethyl acetate (plasma) and Extrelut-1 (urine) extraction, samples are analysed by means of a reversed-phase column (Nova-Pak C18), using a mobile phase consisting of methanol-water-tetrahydrofuran (40:60:4, v/v/v) with UV detection at 230 nm. The chromatography is complete in 10 min and the results show good precision (RSD 1.23-4.49%) and sensitivity for a linear range of 0.4-4.0 micrograms ml-1 for PHT in plasma, 0.1-1.0 microgram ml-1 for PHT in urine and 0.1-1.2 microgram ml-1 for p-HPPH in urine. The results indicate the method to be suitable for pharmacokinetic studies.
authors.affiliation: Centro de Metabolismos e Genética, Faculdade de Farmácia da Universidade de Lisboa, Portugal.
authors.forename: M T
authors.initials: MT
authors.lastname: Maya
authors.forename: A R
authors.initials: AR
authors.lastname: Farinha
authors.forename: A M
authors.initials: AM
authors.lastname: Lucas
authors.forename: J A
authors.initials: JA
authors.lastname: Morais
mesh_terms: D000085:Acetates / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D007692:Diatomaceous Earth; D005663:Furans / Q000737:chemistry; D006801:Humans; D000432:Methanol / Q000737:chemistry; D010672:Phenytoin / Q000031:analogs & derivatives* / Q000097:blood* / Q000652:urine*; D012116:Resins, Plant / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D000085:Acetates; D005663:Furans; D012116:Resins, Plant; D014867:Water; C001419:hydroxyphenytoin; C018674:tetrahydrofuran; D010672:Phenytoin; D007692:Diatomaceous Earth; C018540:Extrelut; C007650:ethyl acetate; D000432:Methanol