A simple method for determination of nimesulide in rat blood samples by high-performance liquid chromatography

A rapid and simple method for determination of nimesulide in blood samples, by high-performance liquid chromatography, was developed. This method includes a single extraction of acidified blood (1N hydrochloric acid) with diethyl ether. Blood extracts were analyzed on a reversed-phase column eluted with a mixture of methanol-0.05 M potassium dihydrogen phosphate solution (pH 5) and detected by absorbance at 290 nm. Retention times for the internal standard and nimesulide were 4.2 and 8.2 min, respectively. The method was linear in the range of 0.2 to 5 mu g/mL and the detection limit of the method was 40 ng/mL. This method is suitable for determination of nimesulide after oral administration, and could be used for pharmacokinetic studies of the drug in the rat using small volume samples.