Stereoselective pharmacokinetics of (R)‐(+)‐ and (S)‐(−)‐rabeprazole in human using chiral LC‐MS/MS after administration of rabeprazole sodium enteric‐coated tablet

Rabeprazole is an effective proton pump inhibitor to treat acid-related diseases. To achieve the simultaneous determination of rabeprazole enantiomers in human plasma, a chiral LC-MS/MS method was developed and validated. Acetonitrile including 0.1% ammonium were used as protein precipitating agent. Analytes were separated within 8 minutes on a Chiralpak IC column (4.6 mm × 150 mm, 5 μm). The mobile phase was 10 mM ammonium acetate including 0.2% acetic acid-acetonitrile (35:65, v/v). An API 4000 mass spectrometer was used as detector for the analysis, and the multiple reactions monitoring transitions of m/z 360.1 → 242.2 and 346.1 → 198.1 were opted for quantifying rabeprazole enantiomers and internal standard. Matrix effects were not apparent for each enantiomer and internal standard (esomeprazole), the calibration curves were linear over the concentration of 0.500 to 400 ng·mL^-1 , the intra-run precisions were below 5.4%, the inter-run precisions were below 9.9%, and the accuracy was between -9.2% and 9.3%. There was no chiral inversion observed during sample storage, preparation procedure, and analysis, demonstrating that analytes were stable in this study. This method was applied to the stereoselective pharmacokinetic study of (R)-(+)- and (S)-(-)-rabeprazole after oral administration of 10-mg rabeprazole sodium enteric-coated tablet in healthy Chinese subjects.