Determination of fexofenadine in human plasma by LC-MS/MS and its application in pharmacokinetic study

This study presented a simple, rapid, and sensitive liquid chromatography analytical method employing tandem mass spectrometry (LC-MS/MS) to determine fexofenadine in human plasma. After the de-proteination procedure with acetonitrile, chromatographic separation of fexofenadine was performed using a reversed-phase Eclipse XDB-C⁸ column with a mobile phase consisted of 1 mmol/L ammonium acetate buffer solution containing 0.2% formic acid-methanol (45:55, v/v). Fexofenadine was quantified using tandem mass detection in the electrospray ionization (ESI) positive ion mode. The flow rate of the mobile phase was 1 mL/min, and the retention times of fexofenadine and the internal standard (IS, losartan) were 1.76 min and 2.65 min, respectively. The calibration curve was linear over the plasma concentration range of 1-1000 ng/mL. The relative standard deviations of intra- and inter-batches were less than 10.4% and 15.4%, respectively. The LC-MS/MS method reported in this study showed higher sensitivity for the quantification of fexofenadine in human plasma than that shown by previously described analytical methods. Lastly, the method was successfully applied to the pharmacokinetic of fexofenadine in healthy Tiwan volunteers.