SIMULTANEOUS ESTIMATION OF DICLOFENAC SODIUM AND TOLPERISONE HYDROCHLORIDE IN COMBINED PHARMACEUTICAL FORMULATION

Three simple, rapid, precise and accurate spectrophotometric methods have been developed for simultaneous analysis of Tolperisone Hydrochloride (TOL) and Diclofenac Sodium (DIC) in their combined dosage form. Method A, Simultaneous equation method (Vierodt’s method) applies measurement of absorptivities at two wavelengths, 261.00 nm (λ_max of Tolperisone Hydrochloride) and 279.00 nm, (λ_max of Diclofenac Sodium) in zero order spectra. The concentrations can be calculated from the derived equations. Method B, Q-Absorbance equation method. It involves formation of Q-absorbance equation at 233.50 nm (isoabsorptive point) and 261.00 nm (λ_max of Tolperisone Hydrochloride) in zero order spectra. Method C, Zero crossing first derivative spectrophotometry involves measurement of absorbance at 249.20 nm (for Tolperisone Hydrochloride) and 227.40 nm (for Diclofenac Sodium) in first derivative spectra. Developed methods were validated according to ICH guidelines. The calibration graph follows Beer’s law in the range of 6.0 to 18.0 μg/ml for Tolperisone Hydrochloride and 2.0 to 6.0 μg/ml for Diclofenac Sodium  with R square value greater than 0.999. Accuracy of all methods was determined by recovery studies and showed % recovery between 98 to 102%. Intraday and interday precision was checked for all methods and mean %RSD was found to be less than 2 for all the methods. The methods were successfully applied for estimation of Tolperisone Hydrochloride and Diclofenac Sodium in marketed formulation