Determination of Apremilast 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) was developed and validated for the determination and pharmacokinetic investigation of apremilast 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 acetonitrile-0.1% formic acid in water with gradient elution. The total run time was 3.0 min, and the elution of apremilast was at 1.27 min. The detection was performed on a triple quadrupole tandem mass spectrometer in the multiple reaction-monitoring mode using the respective transitions m/z 461.3 → 257.1 for apremilast and m/z 237.2 → 194.2 for carbamazepine (internal standard). The calibration curve was linear over the range of 0.1-100 ng/mL with a lower limit of quantitation of 0.1 ng/mL. The mean recovery of apremilast in plasma was in the range of 83.2-87.5%. Both intraday and interday precision were <9.6%. This method was successfully applied in the pharmacokinetic study after oral administration of 6.0 mg/kg apremilast in rats.