A Validated Stability Indicating RP-HPLC Method for Estimation of Amlodipine Besylate and Lisinopril in Pharmaceutical dosage Forms

A simple, precise and accurate stability indicating RP-HPLC method has been developed andsubsequently validated for simultaneous estimation of Amlodipine Besylate (AML) and Lisinopril(LSN) from their combination dosage form. A Shimadzu's HPLC (LC-2010-HT, Shimadzu, Singapore) equipped with UV-Visible and Diode Array detectors, with Class-VP software was used. Column used was Hypersil BDS RP18, 5 μm, 150 mm × 4.6 mm i.d., at 25° C. Mobile phase consisted mixture of solution A (0.05 M Sodium dihydrogen phosphate) and solution B (Acetonitrile) in ratio of 50:50 v/v with flow rate of 1.0 mL/min and UV detection was carried out at 258 nm for AML and LSN, respectively. LSN, AML and their combined dosage form were exposed to thermal, oxidative, acid-base hydrolytic stress conditions, the stressed samples were analyzed by proposed method. Peak purity results suggested no other co-eluting, interfering peaks from excipients, impurities, or degradation products due to variable stress condition, and the method is specific for the estimation of AML and LSN in presence of their degradation products and impurities. The method was validated with respect to linearity, precision, accuracy, system suitability, and robustness. The described method was linear over the range of 12.5–37.5 μg/mL for AML and LSN both. The mean recoveries were in the range of 100.06–100.13% for AML and 99.61–100.31% for LSN, respectively. The intermediate precision data were obtained under different experimental conditions and calculated value of the coefficient of variation (CV, %) was found to be less than critical value. The proposed method can be useful in the quality control of pharmaceuticals.