Abstract

Two new spectrophotometric methods (absorbance ratio method and multiwavelength spectroscopy) for the simultaneous estimation of nimesulide and tizanidine hydrochloride in their combined dosage form have been developed and validated for linearity, accuracy, precision, limit of detection, limit of quantitation and robustness. In the first method, the wavelength selected to develop equations were 297.8 nm and 318.8 nm in methanol for nimesulide and tizanidine respectively and the isoabsorptive point is 302.6 nm. The wavelengths 297.8 nm and 318 nm were selected for the multiwavelength spectroscopy method. Both drugs obeyed Beer-Lambert's law in the concentration range of up to 60 μg/ml for nimesulide and up to 30 μg/ml for tizanidine. The results of both methods have been statistically validated and were found to be satisfactory. These methods were found to be simple, rapid, accurate, precise and reproducible.