title: Phenotype of CYP2C19 and CYP3A4 by determination of omeprazole and its two main metabolites in plasma using liquid chromatography with liquid-liquid extraction.
abstract: We present a new simple and reliable HPLC method for measuring omeprazole and its two main metabolites in plasma. This can be used for studying CYP2C19 and CYP3A4 genetic polymorphisms using omeprazole as the probe drug. Omeprazole, hydroxyomeprazole and omeprazole sulfone were extracted from plasma samples with phosphate buffer and dichloromethane-ether (95:5). HPLC separation was achieved using an Ultrasphere ODS C(18) (Beckman) column. The mobile phase was acetonitrile-phosphate buffer (24:76, pH 8), containing nonylamine at 0.015%. Retention times were 9.5 min for omeprazole, 3.25 min for hydroxyomeprazole, 7.4 min for omeprazole sulfone and 6.27 min for internal standard (phenacetine). Detection (UV at 302 nm) of analytes was linear in the range from 96 to 864 ng/ml. This is useful for calculating metabolic index for CYP2C19 and CYP3A4 in adults and children. This method is stable, reproducible, improves resolution and has practical advantages such as low cost.
authors.affiliation: Laboratories de Investigación y Desarrollo Farmacéutico, Departamento de Farmacobiología, Universidad de Guadalajara, 44840 Guadalajara, Jal, Mexico.
authors.forename: Héctor M
authors.initials: HM
authors.lastname: González
authors.forename: Elba M
authors.initials: EM
authors.lastname: Romero
authors.forename: Teresa de J
authors.initials: Tde J
authors.lastname: Chavez
authors.forename: A Aaron
authors.initials: AA
authors.lastname: Peregrina
authors.forename: Víctor
authors.initials: V
authors.lastname: Quezada
authors.forename: Carlos
authors.initials: C
authors.lastname: Hoyo-Vadillo
mesh_terms: D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D065731:Cytochrome P-450 CYP2C19; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D006899:Mixed Function Oxygenases / Q000235:genetics* / Q000378:metabolism; D009853:Omeprazole / Q000097:blood*; D010641:Phenotype; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet
chemical_list: D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; C104464:CYP3A protein, human; D065731:Cytochrome P-450 CYP2C19; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D009853:Omeprazole