DEVELOPMENT AND VALIDATION OF RP-HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF AMLODIPINE AND VALSARTAN IN ITS BULK AND TABLET DOSAGE FORM BY USING THE QUALITY-BY-DESIGN APPROACH

This study describes the implementation of a Quality by Design approach to develop and validate the RP-HPLC for amlodipine and valsartan. The reaction surface method optimizes by adopting the three-level Box Behnken design. The three factors selected are methanol and water concentrations (mobile phase), flow rate, and wavelength. The developed chromatographic method was validated against the ICH Q2(R1) guidelines for linearity, range, precision, LOD, and LOQ. The maximum absorbance of amlodipine and valsartan (λ max) was found to be 245 nm. The optimized method consists of mobile phase Methanol: Water (pH 3.0) (80:20), and flow rate 0.9 ml/min, which was optimized by using design expert software. Linearity of the developed method was established over the concentration range of 1 10 μg/ml for Amlodipine and 30 – 200 μg/ml with correlation coefficients (r2) of 0.997 and 0.9993, respectively. The percent RSD for accuracy and precision of the method was found to be less than 2%. The limit of detection (LOD) was 0.08 µg/ml and 0.89 µg/ml for Amlodipine and Valsartan, respectively. The limit of quantitation (LOQ) was 0.02 µg/ml and 2.7 µg/ml for Amlodipine and Valsartan, respectively. They are relatively low to permit the determination of low concentrations of the drug.