SIMULTANEOUS ESTIMATION OF ETODOLAC AND THIOCOLCHICOSIDE IN BULK AND IN TABLET FORMULATION BY UV-SPECTROPHOTOMETRY

Two simple, rapid and reproducible simultaneous equation and Q-analysis UV-spectrophotometric methods have been developed for simultaneous estimation of etodolac (ETO) and thiocolchicoside (THC) in combined tablet dosage form. The methods involved solving simultaneous equations and Q-value analysis based on measurement of absorbance at wavelengths, 223 (lambda max of ETO), 259.4 (lambda max of THC) and 236 nm (iso-absorptive point). Linearity was found in the concentration range of 1-6 mu g/mL and 4-24 mu g/mL for ETO and THC, respectively, with correlation coefficients 0.9998 and 0.9992 The amounts of drugs estimated by the proposed methods are in excellent agreement with the label claimed. Furthermore, the methods were applied for the determination of ETO and THC in spiked human urine. The degradation behavior of ETO and THC was investigated under acid hydrolysis, alkali hydrolysis, photo- and oxidative degradation. The subsequently generated samples were used for degradation studies using the developed method. THC was found to degrade extensively under alkali hydrolysis and unaffected by other stress conditions, while ETO was found to be stable in all stress conditions. The methods were validated according to ICH guidelines. The method, suitable for routine quality control, has been successfully applied to the determination of both drugs in commercial brands of tablets.