DETERMINATION OF LANSOPRAZOLE AND 5 METABOLITES IN PLASMA BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A high-performance liquid chromatographic method for the determination of lansoprazole, a new proton-pump inhibitor, and five of its metabol ites in human plasma is described. Lansoprazole. its metabolites, and internal standard (omeprazole) were extracted into diethyl ether-methy lene chloride and separation was obtained using a reversed-phase colum n under isocratic conditions. The method features monochromatic ultrav iolet detection at 285 nm, and single extraction, single evaporation s ample handling. The lower limit of quantitation, based on standards wi th acceptable coefficients of variation, was 10 ng/ml for all compound s. No endogenous compounds were found to interfere. This method has be en demonstrated to be suitable for pharmacokinetic studies in humans.