Rapid and sensitive method for determination of nimesulide in human plasma by high-performance liquid chromatography

A rapid and sensitive high-performance liquid chromatographic method for determination of nimesulide in human plasma has been developed. The chromatographic system uses a reversed-phase C18 column with UV-Vis detection at 230 nm. Mobile-phase consisted of phosphate buffer (pH 5.5)-methanol-acetonitrile (50:20:30, v/v) at a flow-rate of 1.4 ml/min. Nimesulide was extracted in a single step into dichloromethane. The overall mean extraction recoveries were above 98% for both inter- and intra-assay reproducibility, with CVs from 0.3 to 1%. The calibration curve was linear in the concentration range of 0.05-5 microg/ml, and the lower limit of detection was 30 ng/ml. This simple and sensitive method allows for determination of the range of plasma concentrations that is observed after administration of clinically relevant doses of nimesulide.