Experimental Materials and reagentsAll reagents were of analytical-reagent grade unless stated otherwise. Glass-distilled and deionized water (Nanopure II, A simple and rapid reversed-phase high-performance liquid-chromatographic method for the separation and determination of process-related impurities of celecoxib (CXB) in bulk drugs and pharmaceuticals was developed. The separation of impurities viz., 4-methylacetophenone (I), 1-(4-methylphenyl)-4,4,4-trifluorobutane-1,3-dione (II), 4-hydrazinobenzene sulfonamide (III) and a regio-specific isomer [3-(4-methylphenyl)-5-trifluoromethyl-1H-pyrazole-1-yl]-benzenesulfonamide (IV), was accomplished on an Inertsil ODS-3 column dynamically coated with 0.1% hexamethyldisilazane (HMDS) in acetonitrile:water (55:45 v/v) as a mobile phase and detection at 242 nm using PDA at ambient temperature. The chromatographic conditions were optimized by studying the effects of HMDS, an organic modifier, time of silanization and column temperature. The method was validated and found to be suitable not only for monitoring the synthetic reactions, but also to evaluate the quality of CXB.

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11 examples) is synthesized and evaluated for their affinity for adenosine A1/A2A receptors. Derivatives (IIIa) and (IIIb) are the most potent compounds in this series. -(PRASAD*, M. R.; RAO, A. R.; RAO, P. S.; RAJAN, K. S.; MEENA, S.; MADHAVI, K.; Eur. J. Med. Chem. 43 (2008) 3, 614-620; Med. Chem. Lab., Coll. Pharm. Sci., Kakatiya Univ., Warangal 506 009, India; Eng.) -R. Langenstrassen 30-162

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An isocratic reversed-phase high-performance liquid chromatographic method has been developed for separation and simultaneous determination of COX-2 inhibitors, viz., celecoxib, rofecoxib, valdecoxib, nimesulide and nabumetone, using 4-chloro-2-nitroaniline as internal standard. Good chromatographic separation was achieved using a reversed-phase Inertsil C(18) column with mobile phase consisting of methanol and 0.05% aqueous glacial acetic acid (68:32 v/v) using photodiode array (PDA) detector at 230 nm. It was validated with respect to accuracy, precision, linearity, limit of detection and quantification. The linearity range was found to be 1.0--20 microg/mL and the percentage recoveries were between 97.55 and 100.14. The method is suitable not only for the estimation of active ingredients in pharmaceutical dosage forms but also in vitro estimations in human plasma. It is simple, rapid, selective and capable of detecting and determining COX-2 inhibitors with a detection limit of 0.127--1.040 microg/mL simultaneously.