Analytical Approach to Develop and Validate Stability Indicating HPLC Method for Simultaneous Estimation of Tolperisone Hydrochloride and Diclofenac Sodium In Combined Pharmaceutical Dosage Form

A simple and precise stability-indicating high performance liquid chromatography method was developed and validated for the simultaneous estimation of Tolperisone Hydrochloride and Diclofenac Sodium in commercial tablet dosage form. Separation was achieved by using C18 (250mm × 4.6 mm, 5µm) column and mobile phase comprising of potassium dihydrogen phosphate buffer (pH: 6.0): acetonitrile (70:30% v/v) at a flow rate of 1.0ml/min. The detection wavelength was 275 nm. The retention times for Tolperisone Hydrochloride and Diclofenac Sodium were 5.26min and 3.59min, respectively. Linearity of Tolperisone Hydrochloride and Diclofenac Sodium were found in range of 15-52.5µg/ml and 5-17.5µg/ml. The % recovery of Tolperisone Hydrochloride was found to be 99.58%-100.88% and 100.75%-101.33% for Diclofenac Sodium. The values of Limit of detection and limit of quantification were found to be 0.203µg/ml and 0.616µg/ml for Tolperisone Hydrochloride and 0.003µg/ml and 0.010µg/ml for Diclofenac Sodium, respectively. The linear regression coefficient for both drugs was found to be 0.999. The method was found to be robust since the retention times and areas were within the limits even after little deliberate variations in pH, flow rate, mobile phase ratio. Stress studies were conducted on the drug substance and product under the ICH prescribed stress condition viz. hydrolysis, oxidation, photolysis and thermal stress. The drugs showed sufficient decomposition under acidic hydrolysis, alkaline hydrolysis, and oxidation. The drug was found to be moderately sensitive to thermal studies and sunlight studies. This method can be successfully employed for simultaneous quantitative analysis of Tolperisone Hydrochloride and Diclofenac Sodium in pharmaceutical dosage form.