SIMULTANEOUS DETERMINATION OF DICLOFENAC SODIUM AND THIOCOLCHICOSIDE IN FIXED DOSE COMBINATION BY SPECTROPHOTOMETRY

Abstract

Three accurate, precise, sensitive and economical procedures for simultaneous determination of diclofenac sodium and thiocolchicoside in tablet dosage form have been developed. The methods employed were absorbance correction method (I), first order derivative spectroscopic method (II) and dual wavelength method (III). In the first method diclofenac sodium concentration was determined directly from calibration plot by measuring absorbance at 276.6 nm and thiocolchicoside was determined after correction for absorbance of diclofenac sodium at 372.8 nm. The second method is based on first order derivative spectroscopy to overcome spectral interference from other drug. Wavelengths 278.6 nm and 243.2 nm were selected for the determination of the diclofenac sodium and thiocolchicoside, respectively. In the third method, diclofenac sodium was determined by plotting the difference in absorbance at 244 and 269 nm (difference is zero for thiocolchicoside) against the concentration of dicl ofenac sodium. Similarly for the determination of thiocolchicoside, the difference in absorbance at 266.8 and 290 nm (difference is zero for diclofenac sodium) was plotted against the concentration of diclofenac sodium. The Beer's law obeyed in the concentration range 5-30 μg/ml for diclofenac sodium and 10-60 μg/ml for thiocolchicoside. The results of analysis have been validated statistically and by recovery studies.