High performance liquid chromatography–tandem mass spectrometric determination of rupatadine in human plasma and its pharmacokinetics

A simple, rapid, sensitive and selective liquid chromatographic–tandem mass spectrometric (LC–MS/MS) method was developed and validated for the quantification of rupatadine in human plasma using estazolam as internal standard (IS). Following liquid–liquid extraction, the analytes were separated using a mobile phase of methanol–ammonium acetate (pH 2.2; 5 mM) (50:50, v/v) on a reverse phase C18 column and analyzed by a triple-quadrupole mass spectrometer in the positive ion and multiple reaction monitoring (MRM) mode, m/z 416 → 309 for rupatadine and m/z 295 → 267 for the IS. The assay exhibited a linear dynamic range of 0.1–100 ng/ml for rupatadine in human plasma. The lower limit of quantification (LLOQ) was 0.1 ng/ml with a relative standard deviation of less than 20%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The validated LC–MS/MS method has been successfully applied to study the pharmacokinetics of rupatadine in healthy volunteers.