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A simple and enantioselective method was developed and validated for the simultaneous determination of (R)- and (S)-lansoprazole in human plasma by chiral liquid chromatography with tandem mass spectrometry. Lansoprazole enantiomers and internal standard (esomeprazole) were extracted from plasma using acetonitrile as protein precipitating agent. Baseline chiral separation was achieved within 9.0 min on a Chiralpak IC column (150 mm × 4.6 mm, 5 μm) with the column temperature of 30°C. The mobile phase consisted of 10 mM ammonium acetate solution containing 0.05% acetic acid/acetonitrile (50:50, v/v). The mass spectrometric analysis was performed using a QTrap 5500 mass spectrometer coupled with an electrospray ionization source in positive ion mode. The multiple reactions monitoring transitions of m/z 370.1→252.1 and 346.1→198.1 were used to quantify lansoprazole enantiomers and esomeprazole, respectively. For each enantiomer, no apparent matrix effect was found, the calibration curve was linear over 5.00-3000 ng/mL, the intra- and inter-day precisions were below 10.0%, and the accuracy was -3.8 to 3.3%. Analytes were stable during the study. No chiral inversion was observed during sample storage, preparation procedure and analysis. The method was applied to the stereoselective pharmacokinetic studies in human after intravenous administration of dexlansoprazole or racemic lansoprazole., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Lansoprazole, a selective proton pump inhibitor, has a chiral benzimidazole sulfoxide structure and is used for the treatment of gastric acid hypersecretory related diseases. To investigate its stereoselective pharmacokinetics, a column-switching liquid chromatography with tandem mass spectrometry method was developed for the determination of lansoprazole enantiomers in dog plasma using (+)-pantoprazole as an internal standard. After a simple protein precipitation procedure with acetonitrile, matrix components left behind after sample preparation were further eliminated from the sample by reversed-phase chromatography on a C18 column. The fluent was fed to a chiral column for the separation of lansoprazole enantiomers. Baseline separation of lansoprazole enantiomers was achieved on a Chiralcel OZ-RH column using acetonitrile/0.1% formic acid in water (35:65, v/v) as the mobile phase at 40°C. The linearity of the calibration curves ranged from 3 to 800 ng/mL for each enantiomer. Intra- and inter-day precisions ranged from 2.1 to 7.3% with an accuracy of ±1.7% for (+)-lansoprazole, and from 1.6 to 6.9% with an accuracy of ±3.5% for (-)-lansoprazole, respectively. The validated method was successfully applied for the stereoselective pharmacokinetic study of lansoprazole in beagle dog after intravenous infusion., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)