GLC Determination of dl-2-(2-Fluoro-4-Biphenylyl)Propionic Acid (Flurbiprofen) in Plasma

Abstract

To evaluate the pharmacokinetics and drug availability from various dosage formulations, a method for the determination of dl-2-(2-fluoro-4-biphenylyl)propionic acid (flurbiprofen) in human plasma was required. A sensitive and specific procedure, based on (a) benzene extraction of the acidified specimen, (b) TLC of the benzene extract residue, (c) formation of the pentafluorobenzyl esters of the materials eluted from the thin-layer chromatogram, and (d) quantification of the pentafluorobenzyl esters by GLC, utilizing electron-capture detection, was developed. The lower level of assay detection sensitivity for measurement of flurbiprofen in plasma is 0.05 μg/ml. Statistical analyses indicated an average recovery of 97.1% with a standard deviation of ±9.2%. IR and mass spectrometric analyses, in conjunction with GLC, confirmed the specificity of the method for the intact drug. The procedure was successfully applied to drug absorption studies in humans.