A simple, sensitive gradient rapid resolution liquid chromatographic assay method has been developed for the quantitative determination of Candesartan Cilexetil in bulk active pharmaceutical ingredient, used for the treatment of hypertension. The developed method is also applicable for the process related impurities determination. Efficient chromatographic separation was achieved on a C18 stationary phase with simple mobile phase combination delivered in a gradient mode and quantification was by ultraviolet detection at 210 nm at a flow rate of 0.4 mL·min −1. In the developed UPLC method the resolution between Candesartan Cilexetil and its two potential impurities was found to be greater than 2.0. Regression analysis showed an r value (correlation coefficient) greater than 0.99 for Candesartan Cilexetil and its two impurities. This method was capable to detect two impurities of Candesartan Cilexetil at a level of 0.003% with respect to test concentration of 1.0 mg·mL −1 for a 2 μL injection volume. The bulk active pharmaceutical ingredient was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. Considerable degradation was found to occur in oxidative stress conditions. The stress samples were assayed against a qualified reference standard and the mass balance was found close to 99.5%. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness.

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