Determination of Pemirolast in Human Plasma by LC-MS and Study of Its Pharmacokinetics

AIM: To establish an LC-MS method for the study of pharmacokinetics and bioavailability of pemirolast in human plasma.METHOD:After adding paracetamol,the internal standard,and 1 mol/L HCl 100 μl,the plasma samples were extracted with methylene chloride-ethyl acetate(20∶80,v/v) and determined by LC-MS.Analysis was performed with the mobile phase consisting of CH_ 3OH-20 mmol/L NH_ 4Ac,pH 3.0(50∶50,v/v)at the flow rate of 0.2 ml/min.Concentrations of pemirolast in plasma of 20 male volunteers after oral administration of 10 mg pemirolast test and reference tablets were determined by the random two-way cross-over design.Pharmacokinetic parameters were also estimated.RESULT: The assay exhibited a linear range from 10 to 1 000 ng/ml with the correlation coefficient of 0.999 3.The limit of detection was 5 ng/ml.For the test and reference tablets,t_ max were (2.2±0.6) h and (2.1±0.6) h,c_ max were (142.48±83.96) ng/ml and (140.34±61.90) ng/ml,AUC_ 0-∞ were (568.13±194.74) ng·h/ml and (587.35±232.24) ng·h/ml,t_ 1/2 were (2.53±0.52) h and (2.67±0.37) h respectively.CONCLUSION: The two formulations are proved to be bioequivalent and the method was simple,sensitive and rapid.