Determination of Linagliptin in Rat Plasma by UPLC-MS/MS and its Application to a Pharmacokinetic Study

A rapid, sensitive and selective ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the determination and pharmacokinetic investigation of linagliptin in rat plasma. Sample preparation was accomplished through a simple one-step deproteinization procedure with 0.2 mL of acetonitrile to a 0.1 mL plasma sample. Plasma samples were separated by UPLC on an Acquity UPLC BEH C18 column using a mobile phase consisting of ace-tonitrile-0.1% formic acid in water with gradient elution. The total run time was 3.0 min and the elution of linagliptin was at 1.09 min. The detection was performed on a triple quadrupole tandem mass spectrometer in the multiple reaction-monitoring (MRM) mode using the respective transitions m/z 473.2 -> 420.3 for linagliptin and m/z 285.2 -> 193.2 for diazepam (internal standard), respectively. The calibration curve was linear over the range of 0.1-20 ng/mL with a lower limit of quantitation (LLOQ) of 0.1 ng/mL. Mean recovery of linagliptin in plasma was in the range of 76.1-82.2%. Intra-day and inter-day precision were both < 8.4%. This method was successfully applied in pharmacokinetic study after oral administration of 1.0 mg/kg linagliptin in rats.