Dogrukol-Ak, Tuncel, Aboul-Enein 743 Dilek Dogrukol-Ak a) , Muzaffer Tuncel a) , Hassan Y. Aboul-Enein b) a) Department of Analytical Chemistry, Faculty of Pharmacy, Anadolu University, 26470-Eskisehir, Turkey b) Pharmaceutical Analysis Laboratory, Biological & Medical Research Department, MBC-03, King Faisal Specialist Hospital & Research Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia A capillary zone electrophoretic method for the determination of nimesulide in pharmaceutical preparation and serum A simple capillary zone electrophoretic (CZE) method was developed to determine nimesulide in pharmaceutical tabletformulations and serum. Method development was conducted in a fused-silica capillary using a background electrolyte of 10 mM borate buffer containing 10% ethanol at pH 8.1, injecting for 1 s by vacuum injection, applying 30 kV.Salicylic acid was found to be a good internal standard (IS)and detection was performed at 200 nm. Nimesulide and IS appeared at average migra- tion times (RSD%) of7.2 (0.75%) and 10.4 (0.91%) min, respectively. The limitof detection (S/N = 3)and limit of quantitation (S/N = 10) were 2.2610 – 6 M and 6.7610 – 6 M, respectively. The method was applied to the tablets containing 100 mg nimesulide and the results were compared to those of UV-spectrophotometry. The recoveries of methods (as mean (mg) l RSD%) were found to be 99.6 l 1.59 for CZE and 98.9 l 1.04 for UV spectrophotometry. The proposed method was also applied for the determination of nimesulide in serum by the standard addition technique. The proposed method is sensitive, precise, and easy to use for the determination of nime- sulide in tablets and serum. Key Words: Nimesulide; Capillary zone electrophoresis; Pharmaceutical analysis Ms received: January 31, 2001; revised: April 3, 2001; accepted: April 10, 2001 1 Introduction Nimesulide (4-nitro-2-phenoxymethanesulphonanilide) (NMS, Figure 1) is a nonsteroidal anti-inflammatory drug (NSAID) of the sulfonanilide class with analgesic and anti- pyretic properties. It was reported that NMS is an effective and well tolerated alternative to other NSAIDs in the short term treatment of pain and inflammation of osteoarthritis and various other causes [1]. Further, NMS is a relatively weak inhibitor of prostaglandin synthesis in vitro and ap- pears to exert its effects through a variety of mechanisms including free-radical scavenging, effects on histamine re- lease, the neutrophil myeloperoxidase pathway, bradyki- nin activity, tumor necrosis factor a-release, cartilage de- gradation, metalloprotease synthesis, phosphodiesterase type IV inhibition, plateletaggregation, and synthesis of platelet activating factor. NMS is extensively metabolized to several metabolites which are excreted mainly in the ur- ine or feces. The drug is almost completely transformed to 4-hydroxynimesulide in both free and conjugated forms and this metabolite appears to contribute to the anti-in- flammatory activity of the compound [1]. Severalmethods have been reported for the determina- tion of NMS and its major metabolite 4-hydroxynimesulide in plasma and urine by HPLC [2 – 8] and HPTLC [9]. Sev- eral methods have been described for analysis of NMS in pharmaceuticaltablet formulations including HPLC [10,11], voltammetry [12], polarography [13], HPTLC [14], spectrophotometry [15 – 20] and fluorometry [21]. pK a de- termination of NMS has been reported using potentio- metric [22] and spectrophotometric [23] methods. The aim of this study is to develop a simple, rapid, and ac- curate capillary zone electrophoretic method for the deter- mination of NMS in tablets and serum. The method was validated by comparing the results to those of UV spectro- photometry. J. Sep. Sci. 2001, 24, 743–748 Correspondence: Prof. Hassan Y. Aboul-Enein,Pharma- ceuticalAnalysis Laboratory, Biological & MedicalResearch Department, MBC-03, King Faisal Specialist Hospital & Re- search Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia. E-mail: enein@kfshrc.ed.sa Fax: +966 1 442 7858 Original Paper i WILEY-VCH Verlag GmbH, D-69451 Weinheim 2001 1615-9306/2001/0909–0743$17.50+.50/0 Figure 1. The chemical structure of nimesulide.