Development of a highly sensitive LC-MS/MS method for simultaneous determination of rupatadine and its two active metabolites in human plasma: Application to a clinical pharmacokinetic study.

An easy LC-ESI-MS/MS method was developed and validated for simultaneous determination of rupatadine (RT) and its two active metabolites, namely desloratadine (DT) and 3-hydroxydesloratadine (3-OH-DT), in human plasma. The chromatographic separation was carried out on a C18 column with gradient elution by using methanol and 10mM ammonium acetate containing 0.1% (v/v) formic acid. The lower limit of quantification (LLOQ) was 0.05, 0.035 and 0.035 ng/mL for RT, DT and 3-OH-DT, respectively. The intra- and inter-day precision of analytes were within the range of 1.0-4.7% and 2.2-12.1%, respectively. The intra- and inter-day accuracy of analytes were within the range of -7.7% to 5.2% and -4.1% to 4.8%, respectively. The method was successfully applied to a pharmacokinetic study of RT and its two metabolite DT and 3-OH-DT in healthy volunteers following single (10, 20, 40 mg) and multiple (10 mg) oral doses of rupatadine fumarate tablets.