SIMULTANEOUS DETERMINATION OF RUFLOXACIN, FENBUFEN AND FELBINAC IN HUMAN PLASMA USING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A simple, specific and sensitive high-performance liquid chromatograph ic method has been developed for the simultaneous determination of ruf loxacin, fenbufen and felbinac in human plasma. Plasma, spiked with in ternal standard, was vortex-mixed for 1 min with a mixture of dichloro methane-diethyl ether (80:20, v/v). The evaporated extract was dissolv ed in 0.02 M NaOH. Drugs were resolved at room temperature on a 5 mu m Zorbax SAX column (250X4.6 mm I.D.) equipped with a 20X4.6 mm anion-e xchange Vydac AXGU (10 mu m particle size) precolumn. The mobile phase consisted of acetonitrile and phosphate buffer (pH 7.0): delivered at a flow-rate of 1.2 ml/min. Detection was made at 280 nm. 2-[4-(2'-Fur oyl)phenyl]propionic acid was used as internal standard. The calibrati on curve was linear from 0.2 to 10 mu g/ml for rufloxacin, from 0.5 to 30 mu g/ml for fenbufen and from 0.2 to 10 mu g/ml for felbinac, resp ectively. The detection limit was 0.1 mu g/ml for rufloxacin, 0.3 mu g /ml for fenbufen and 0.1 mu g/ml for felbinac, respectively.