Study On The Determination Of Fexofenadine In Human And The Bioequivalence Evaluation

AIM: Develop a rapid and sensitive method for the determination of fexofenadine in human plasma by liquid chromatography-mass spectrometry (LC-MS/MS). For the bioequivalence study.STUDY METHOD: Fexofenadine and the internal standard, diphenhydramine, were precipitated from the matrix by acetonitrile, then washed with dichloromethane and separated on a Zorbax-extend C18 column employing a 1% formic acid/methanol gradient system. Detection was carried out by multiple reaction monitoring (MRM) on an API 4000 LC-MS/MS system with an ESI interface in the positive ion mode. MRM was performed at low resolution using the mass transition ion-pairs m/z 502→m/z 466.4 and m/z m/z 256.1→m/z 167.1 for fexofenadine and diphenhydramine , respectively. The linearity, specificity, precision, accuracy, recovery and stability were estimated for the validations of the assay.The concentrations of fexofenadine in human plasma were measured after oral administration of fexofenadine at 120 mg. After the plasma concentration–time profile was shown, the area under the curve (AUC0-t) was determined by the linear trapezoidal rule. The two one-sided tests procedure carried out at a significance level of 0.05, and the mean Jinsai fexofenadine LAR/sandostatin LAR ratios of AUC0?t (after log-transformed) were computed. RESULTS: A highly selective, sensitive, rapid and reproducibility method for the determination of fexofenadine in human plasma by using LC-MS/MS has been developed and validated in this study. The standard curve of fexofenadine was linear over a working range of 1.0-1000 ng?mL-1 with the lower limit of quantitation (LLOQ) of 1.0 ng?mL-1 and the limit of detection (LOD) of 0.2 ng?mL-1. The accuracy was in the range 90.1-109% and the intra- and inter-day precision was <8.37%. It showed relative high and stable recovery for the sample preparing procedure. The samples were stable in three freeze-thaw cycles test, in the autosampler at room temperature for 12 h and in storage at ?20°C for 30 days. The methods, which kept the conformance to the relevant standards of Pharmacopoeia of People's Republic of China, were ideally suited for the study of pharmacokinetics of fexofenadine.The results of bioequivalence evaluation of fexofenadine showed that: The mean AUC0-t of Agilent after oral administration at dose of 120 mg was 2655±728 ng?h?mL-1, while that of Kewen fexofenadine LAR with the same administration dose was 2655±728 ng?h?mL-1. The relative bioavailability of Kewen fexofenadine tablet was 98.12%. The two one-sided tests illustrated that there was no significant difference in bioavailability of the two tablet formulations.