Spectrophotometric Determination of Nimesulide in Pure and in Pharmaceutical Formulations Using Ion-associate Complex Formation

INTRODUCTION Nimesulide is a relatively cyclo-oxygenase-2 (COX2) selective, non-steroidal anti-inflammatory drug (NSAID) with analgesic and antipyretic properties. Its approved indications are the treatment of acute pain, the symptomatic treatment of osteoarthritis and primary dysmenorrhoea in adolescents and adults above 12 years old to decrease the risk of hepatotoxicity. It may be used orally or rectally or topically. It has the potential to reduce the incidence ABSTRACT Simple, rapid, and sensitive direct spectrophotometric methods for the determination of nimesulide (NIM) in pure form and pharmaceutical formulations have been developed. The methods depend on the formation of colored ion-pair complexes between NIM and three different reagents, bromocresol green (BCG), bromocresol purple (BCP) and brilliant blue G (BBG) in Britton-Robinson (B-R) universal buffer solutions. The colored complexes were measured directly exhibiting λ max at (554, 437 and 643 nm) for BBG, BCP and BCG respectively. The analytical parameters and their effects were investigated. The ion-pair complexes are intensely colored and very stable at room temperature. The calibration graphs were linear over the concentration range of 2 12 μg/mL for BCP, 2-14 μg/mL for BCG and 2-13 μg/mL BBG. The stoichiometry of the reaction was found to be 1: 1 in all cases. The proposed methods were successfully extended to pharmaceutical preparations in tablet dosage form.