Determination of apremilast concentration in human plasma UHPLC-MS/MS and its bioequivalence study
Objective To develop an UHPLC-MS/MS method for determination of apremilast in human plasma and the bioequivalence study.Methods Plasma sample was treated with methanol for protein precipitation while apremilast-d5 was used as internal standard(IS).Separation was achieved on a Phenomenex Kinetex C18 column(2.1 mm×50 mm,2.6μm)by gradient elution at a flow rate of 0.45 mL·min-1,with acetonitrile(containing 0.1%of formic acid)and water(containing 0.1%formic acid)as mobile phase.Detection was performed using electrospray ionization in positive ion multi-ple reaction monitoring(MRM)mode for three minutes.Results Calibration curves of apremilast were linear in the con-centration range of 2~600 ng·mL-1(r2=0.997 7),with precisions and accuracies were less than 15%.The 90%confidence intervals of AUC0~t,AUC0~∞ and Cmax of the test preparations of Apremilast Tablets under fasting and postprandial conditions were within the ranges of 80.0%~125.0%of the corresponding parameters of the reference preparation.Conclu-sion The test preparation and reference preparation are bioequivalent.