Abstract

A simple high-performance liquid chromatographic method for the determination of etoricoxib in human plasma has been developed. An aliquot quantity of 1 ml plasma sample was taken and 10 ml internal standard was added and mixed. Saturated borate solution of 0.3 ml was added to it and mixed for 1 minute followed by liquid-liquid extraction with ethyl acetate. Organic layer was separated and evaporated to dryness under nitrogen atmosphere at low temperature (below 50°). Residue was reconstituted with 150 µl of mobile phase. During the whole procedure the samples were protected from light. The assay was performed on Hypersil BDS, C18 (150×4.6 mm, 5 m particle size) column, using 10 milimol ammonium acetate buffer:acetonitrile = 65:35 v/v as mobile phase with ultra violet detection at 235 nm. Lower limit of detection was 10 ng/ml and lower limit of quantitation was 20 ng/ml. Maximum between-run precision was 7.94%. Mean extraction recovery was found to be 79.53 to 85.70%. Stability study showed that after three freeze-thaw cycles the loss of three quality control samples were less than 10%. Samples were stable at room temperature for 12 h and at -20° for 3 months. Before injecting onto HPLC system, the processed samples were stable for at least 8 h. The method was used to perform bioequivalence study in human.