DEVELOPMENT AND VALIDATION OF STABILITY INDICATING ANALYTICAL METHOD FOR SIMULTANEOUS ESTIMATION OF CILNIDIPINE, CHLORTHALIDONE AND TELMISARTAN IN BULK AND TABLET DOSAGE FORM

A simple, accurate and precise method was developed for the simultaneous estimation of cilnidipine, chlorthalidone and telmisartan in tablet dosage form on Agilent C18 column (150mmx4.6mm dia., 5µ particle size), using buffer and acetonitrile in the ratio of 55:45 V/V, which was pumped through the column with a flow rate of 1mL/min.The buffer used in this method was 0.1% orthophosphoric acid at a pH of 2.5.The run time was 5 min. and the retention time of cilnidipine, chlorthalidone and telmisartan were found to be2.105min, 2.813min and 3.505min. Reference standard solutions of the drugs were prepared by dissolving firstly in methanol and then diluting with methanol and water (50:50 V/V). This method provides good linearity (R2 =0.999) over a range of 5-30µg/mL of cilnidipine,6.25-37.5µg/mL of chlorthalidone and 20-120µg/mL of telmisartan. Optimized wavelength was 238nm. The method was validated in terms of specificity, linearity, accuracy, precision, detection limit, quantification limit, robustness and forced degradation.