Stereospecific high-performance liquid chromatographic analysis of flurbiprofen: application to pharmacokinetic studies.

A method of analysis of flurbiprofen (+/- 2-(2-fluoro-4-biphenyl)-propionic acid) in biological fluids is necessary to study the kinetics of in vitro and in vivo metabolism and tissue distribution. A simple high-performance liquid chromatographic method was developed for simultaneous determination of flurbiprofen enantiomers in rat serum. Serum (0.1 ml) was extracted with 2,2,4-trimethylpentane-isopropanol (95:5, v/v) after addition of the internal standard (IS), S-naproxen and acidification with H(2)SO(4). Separation was achieved on a Chiralpak AD-RH column with UV detection at 247 nm. The calibration curve was linear ranging from 0.05 to 50 microg/ml for each enantiomer. The mean extraction efficiency was >95%. Precision of the assay was <11% (CV), and was within 12.6% at the limit of quantitation (LOQ) (0.05 microg/ml). Bias of the assay was lower than 13.1%, and was within 12.8% at the LOQ. The assay was applied successfully to the in vivo kinetic study of flurbiprofen in rats.