LC-MS Estimation of Fenofibric Acid in Microvolumes of Human Plasma and Its Application to Bioequivalence Study

A rapid, specific and robust bioanalytical method for quantification of fenofibric acid, the active form of fenofibrate, a hypolipidemic agent, was developed and validated in micro volumes (35 mu L) of human plasma by liquid chromatography-electrospray ionization tandem mass spectrometry in negative ion mode. Fluvastatin was used as an internal standard. Precursor to product ion transitions of m/z 317.0 -> 231.0 and m/z 410.2 -> 348.1 were used to measure the analyte and the internal standard (ISTD), respectively. Chromatographic separation was carried out in reverse phase conditions using Chromolith SpeedRod RP-18e column (50 mm x 4.6 mm i.d.) with an isocratic mobile phase consisting of water/acetonitrile (20/80, v/v, pH 6.5) at a flow rate of 0.7 mL min(-1). The extraction procedure yielded a recovery of 104.06 and 95.57% for fenofibric acid and the internal standard, respectively. The assay exhibited a linear dynamic range of 0.05-14.84 mu g mL(-1). The RSD% of intra- and inter-day assay was a parts per thousand currency sign15%. For its sensitivity, reliability and lower plasma volume requirement, the proposed method is suitable for pharmacokinetic studies.