UV-Spectrophotometric and Stability Indicating RP-HPLC Method for the Simultaneous Estimation of Amlodipine Besylate and Indapamide

Abstract

A UV-spectrophotometric and stability-indicating RP-HPLC method was developed and validated for concurrent estimation of Amlodipine besylate (AMDB) and Indapamide (INDA) in combined tablet dosage form in the presence of degradation products generated from stress degradation studies. For the RP-HPLC; Chromatography was carried on Shimadzu LC-20AT series HPLC; C-18 ODS bonded column (25 cm × 4.60 mm, 10 μl, 40°C) used as stationary phase; methanol: water (95:5% v/v) as mobile phase. The retention time of the AMDB and INDA were 8.780 and 2.850 min, respectively; detection at λmax 238 nm for both of drug (overlain spectra). Linear regression analysis shows a good linear relationship; in the concentration range of 2-16 μg/ml and 1-7 μg/ml; for AMDB and INDA with r > 0.999. These methods were accurate with a relative standard deviation of less than 2% for both drugs. Stress conditions like acid, alkali degradation, hydrolytic, thermal and oxidation were applied and quantify by the RP-HPLC method. The degradation products did not interfere with the detection of AMDB and INDA, thus the method can be considered as a stabilityindicating method. The UV-spectrophotometric simultaneous equation method was based on the measurement of absorbance at two wavelengths; the λmax for AMDB and INDA was found to be 237 & 242 nm respectively for analytical measurement. The drugs AMDB and INDA follow the Beer’s law in the concentration range of 5-25 μg/ml and 1-11 μg/ml, respectively; showing correlation coefficient (r) of 0.9980 for AMDB and 0.9990 for INDA. These methods were successfully applied for reliable quantification of AMDB and INDA in commercial and routine analysis in combined dosage form.