A comparative study of two separate analytical techniques for the simultaneous determination of diclofenac sodium and diacerein from combined dosage form

Diclofenac sodium (DS) and diacerein (DC) have emerged as a potential combination therapy for the treatment of knee osteoarthritis. Therefore a validated analytical method is essential for the simultaneous estimation of both from combined dosage form. A ratio derivative spectrophotometric and a chromatographic technique have been developed for the simultaneous determination of DS and DC. The quantification was done at 263.00 nm for DC and 304.50 nm for DS in the first method, whereas 257 nm for DC and at 274 nm for DS for LC-DAD analysis in chromatographic method using acetate buffer and methanol as the mobile phase at a flow-rate 0.50 mL/min. Both of these methods are found to be linear in the concentration range under study with r2 value 0.999 and 0.996 for DS and DC respectively in ratio derivative spectroscopy and 0.998 and 0.999 for DS and DC respectively in LC-DAD study. Both of these methods are found to be accurate and precise, though greater robustness and precision is observed with chromatographic analysis over the ratio derivative spectroscopy. Statistically there was no significant difference between proposed ratio derivative spectrophotometric and LC-DAD methods