Sensitive determination of omeprazole and its two main metabolites in human plasma by column-switching high-performance liquid chromatography: application to pharmacokinetic study in relation to CYP2C19 genotypes.
A simple and sensitive column-switching high-performance liquid chromatographic method was developed for the simultaneous determination of omeprazole and its two main metabolites, 5-hydroxyomeprazole and omeprazole sulfone, in human plasma. Omeprazole, its two metabolites and lansoprazol as an internal standard were extracted from 1 ml of alkalinized plasma sample using diethyl ether-dichloromethane (45:55, v/v). The extract was injected into a column I (TSK-PW precolumn, 10 microm, 35 mm x 4.6 mm i.d.) for clean-up and column II (Inertsil ODS-80A column, 5 microm, 150 mm x 4.6mm i.d.) for separation. The mobile phase consisted of phosphate buffer-acetonitrile (92:8 v/v, pH 7.0) for clean-up and phosphate buffer-acetonitrile-methanol (65:30:5 v/v/v, pH 6.5) for separation, respectively. The peak was detected with an ultraviolet detector set at a wavelength of 302 nm, and total time for chromatographic separation was approximately 25 min. The validated concentration ranges of this method were 3-2000 ng/ml for omeprazole, 3-50 ng/ml for 5-hydroxyomeprazole and 3-1000 ng/ml for omeprazole sulfone. Mean recoveries were 84.3% for omeprazole, 64.3% for 5-hydroxyomeprazole and 86.1% for omeprazole sulfone. Intra- and inter-day coefficient variations were less than 5.1 and 6.6% for omeprazole, 4.6 and 5.0% for 5-hydroxyomeprazole and 4.6 and 4.9% for omeprazole sulfone at the different concentrations. The limits of quantification were 3 ng/ml for omeprazole and its metabolites. This method was suitable for use in pharmacokinetic studies in human volunteers, and provides a useful tool for measuring CYP2C19 activity.
Department of Clinical Pharmacology, Hirosaki University School of Medicine, Hirosaki 036-8562, Japan.
Mikiko
M
Shimizu
Tsukasa
T
Uno
Takenori
T
Niioka
Norio
N
Yaui-Furukori
Takenori
T
Takahata
Kazunobu
K
Sugawara
Tomonori
T
Tateishi
D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D065731:Cytochrome P-450 CYP2C19; D005260:Female; D005838:Genotype; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D006899:Mixed Function Oxygenases / Q000235:genetics*; D009853:Omeprazole / Q000097:blood* / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet
D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19; D009853:Omeprazole