Quantitation of Apremilast in Beagle Dogs Plasma by UPLC-MS-MS and Its Application to Pharmacokinetic Studies

A sensitive and selective ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) method for the determination of apremilast in beagle dog plasma has been developed and successfully validated in the current study. Clopidogrel was employed as an internal standard (IS), and liquid-liquid extraction by tert-butylmethyl ether was used for sample preparation. Chromatographic separation was achieved on a UPLC BEH Shield RP18 column (50 mm × 2.1 mm, 1.7 μm) with 5 mM ammonium formate water and 5 mM ammonium formate methanol as the mobile phase with gradient elution. Calibration plots were linear in the range of 2-3000 ng/mL for apremilast in beagle dog plasma. Mean recoveries of apremilast in beagle dogs plasma ranged from 87.4% to 97.4%. The intrarun and interrun precision was less than 6% and 9%, respectively, with the accuracy between 92.4% and 101.1%. The method has also been successfully applied in the pharmacokinetics study of apremilast. The mean t1/2Z was 5.41 h for 30 mg·day^-1 for beagle dogs after oral administration. The AUC0-t increased linearly from 3.51 to 1802.13 μg L^-1 ∗h after administration of single doses.