A high performance liquid chromatography-tandem mass spectrometric method for the determination of mefenamic acid in human plasma: Application to pharmacokinetic study

Abstract

In the present study, the development and validation of an LC-MS/MS method for quantifying mefenamic acid in human plasma is described. The method involves liquid-liquid extraction using diclofenac as an internal standard (IS). Chromatographic separation was achieved on a Thermo Hypurity C18, 50×4.6mm, 5μm column with a mobile phase consisting of 2m m ammonium acetate buffer and methanol (pH 4.5 adjusted with glacial acetic acid; 15:85, v/v) at a flow-rate of 0.75mL/min and the total run time was 1.75min. Analyte was introduced to the LC-MS/MS using an atmospheric pressure ionization source. Both the drug and IS were detected in negative-ion mode using multiple reaction monitoring m/z 240.0→196.3 and m/z 294.0→250.2, respectively, with a dwell time of 200ms for each of the transitions. The standard curve was linear from 20 to 6000ng/mL. This assay allows quantification of mefenamic acid at a concentration as low as 20ng/mL in human plasma. The observed mean recovery was 73% for the drug. The applicability of this method for pharmacokinetic studies has been established after successful application during a 12-subject bioavailibity study. © 2012 John Wiley & Sons, Ltd..