title: Determination of S/R ratio of mephenytoin in human urine by chiral HPLC and ultraviolet detection and its comparison with gas chromatography.
abstract: OBJECTIVE
  To improve HPLC method for rapid determination of urinary S/R-ratio of mephenytoin, a widely used metabolic index for cytochrome P-450 2C19 (CYP2C19) activity.
  
  
  METHODS
  Aliquots of 0-8-h urine sample after dosing racemic mephenytoin 100 mg underwent one-step extraction with dichloromethane. Analysis was performed on a chiral column (250 mm x 4 mm, 5 microns) at lambda = 207 nm. The eluent was a mixture of acetronitrile and water containing both 0.1% glacial acetic acid and 0.2% triethylamine (14:86, vol/vol) at a flow-rate of 0.9 mL.min-1.
  
  
  RESULTS
  The enatiomers of mephenytoin in urine were well separated within 9 min. A linear correlation was observed between 50-5000 micrograms.L-1 with the detection limit of 12.5 micrograms.L-1 for both enantiomers of mephenytoin. This HPLC analysis was comparable to gas chromatography in accuracy and sensitivity, but with much shorter retention time and better resolution.
  
  
  CONCLUSIONS
  The present HPLC method is good for rapid determination of the ability of subjects to hydroxylate S-mephenytoin after oral administration of the racemic drug.
authors.affiliation: Pharmacogenetics Research Institute, Hunan Medical University, Changsha, China.
authors.forename: S L
authors.initials: SL
authors.lastname: Huang
authors.forename: H G
authors.initials: HG
authors.lastname: Xie
authors.forename: W
authors.initials: W
authors.lastname: Wang
authors.forename: Z H
authors.initials: ZH
authors.lastname: Xu
authors.forename: C H
authors.initials: CH
authors.lastname: Jiang
authors.forename: H H
authors.initials: HH
authors.lastname: Zhou
mesh_terms: D001189:Aryl Hydrocarbon Hydroxylases; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D065731:Cytochrome P-450 CYP2C19; D003577:Cytochrome P-450 Enzyme System / Q000652:urine*; D006801:Humans; D008617:Mephenytoin / Q000652:urine*; D006899:Mixed Function Oxygenases / Q000652:urine*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19; D008617:Mephenytoin