Aim: To improve and validate an analytical method based on liquid chromatography and electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) for the quantitative measurement of ilaprazole and its two metablites in human plasma. Methods: Separation of analytes and the internal standard (IS), omeprazole, was performed on a Thermo HyPURITY C18 column (150×2.1 mm, 5 µm) with a mobile phase consisting of 10 mmol/L ammonium formate water-acetonitrile solution ( Results: The method was linear over the concentration range of 0.23−2400.00 ng/mL for ilaprazole, 0.05−105.00 ng/mL for ilaprazole thiol ether and 0.06−45.00 ng/mL for ilaprazole sulfone. The intra-and inter-day precisions were all less than 15% in terms of relative standard deviation (RSD), and the accuracy was within 15% in terms of relative error (RE) for ilaprazole, ilaprazole sulfone and ilaprazole thiol ether. The lower limit of quantification (LLOQ) was identifiable and reproducible at 0.23, 0.05 and 0.06 ng/mL with acceptable precision and accuracy for ilaprazole, ilaprazole sulfone and ilaprazole thiol ether, respectively. Conclusion: The validated method offered sensitivity and a wide linear concentration range. This method was successfully applied for the evaluation of the pharmacokinetics of ilaprazole and its two metabolites after single oral doses of 5 mg ilaprazole to 12 healthy Chinese volunteers.

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We identified ORM1 as another polymorphic gene affecting warfarin dose requirements. ORM1 S carriers require lower maintenance doses to achieve and maintain an optimal level of anticoagulation.