Simulataneous Determination of Nimesulide and its Impurities in Pharmaceutical Formulations by Reversed-Phase High-Performance Liquid Chromatography

B. Tubić^a*, B. Ivković^b, M. Zečević^b and S. Vladimirov^b
a Drug Agency of the Republic of Srpska, Veljka Mladjenovi}a bb., 78 000 Banja Luka, Bosnia and Herzegovina
^b Institute of Pharmaceutical Chemistry and Drug Analysis, Faculty of Pharmacy,
 University of Belgrade 450 Vojvode Stepe St., P.O. Box 146, Belgrade 11152, Serbia
 E-mail: b.tubic@spinter.net

Abstract
A simple, rapid and reproducible reversed-phase high-performance liquid chromatography method for the analysis of  nimesulide and its impurities both in the bulk drug and pharmaceutical formulations is reported. The method is suitable for monitoring the stability of nimesulide. The presence of nimesulide impurities C (2-phenoxyaniline) and D (2-phenoxy- 4-nitroaniline) was observed. The best separation was achieved using an Agilent Zorbax Extend C₁₈ column (150 × 4.6 mm, particle size 5 µm) at 40 °C and flow rate of 1.0 mLmin^–1. The analytes were monitored at 230 nm. The mobile phase consisted of acetonitrile – triethylamine (TEA) – water (45:0.5:54.5 v/v/v), adjusted to pH 5.2 with formic acid. Under these conditions the retention times were of 7.11, 7.98 and 8.66 min for nimesulide, D and C, respectively. The resolution of nimesulide and impurity D was 3.20 and that of impurity D and impurity C 2.40, indicating that the compounds were well separated. Evaluation of linearity, accuracy, precision, selectivity, sensitivity and robustness of the method produced satisfactory results. The developed method was successfully applied to assay nimesulide in different solid pharmaceutical formulations.

Keywords: Nimesulide, impurities, degradation products, RP-HPLC.