Development and validation of a liquid chromatography/tandem mass spectrometry assay for the simultaneous determination of dabigatran etexilate, intermediate metabolite and dabigatran in 50 μL rat plasma and its application to pharmacokinetic study

A simple, rapid and specific high performance liquid chromatography-electrospray ionization tandem mass spectrometry method was developed for simultaneous determination of dabigatran etexilate (BIBR 1048 MS), the intermediate metabolite (BIBR 1087 SE) and dabigatran (BIBR 953 ZW). In this method, a stacked protein precipitation with methanol was performed in Sirocco 96-well filtration plates to extract analytes using only 50 μL plasma. The analysis was performed on an Ultimate TM XB-C18 (4.6 × 50 mm, 5 μm) column using gradient elution with a mobile phase composed of methanol containing 0.01% formic acid and pure water at a flow rate of 0.3 mL/min. The gradient was set to 90% methanol containing 0.01% formic acid for the first 1.0 min, after which it dropped to 10%, and then was kept at 10% for the next 5 min followed by an additional 1.0 min at the initial composition of 90% methanol containing 0.01% formic acid for equilibration. Detection was performed on a triple-quadrupole mass spectrometer electrospray ionization interface in positive ion mode. Linear calibration curves were obtained over the concentration ranges of 1-500 ng/mL for all analytes. The validated LC-MS/MS method for its selectivity, sensitivity, linearity, precision, accuracy, recovery, matrix effect and stability had been successfully applied to a pharmacokinetic study of analytes in rat plasma following a single oral administration of 15 mg/kg dabigatran etexilate.