A new stability indicating high performance liquid chromatography (HPLC) method has been developed and validated for the quantitative determination of potential impurity of rupatadine fumarate drug substance and drug product. A simple, specific, precise, robust and reproducible reverse high phase performance liquid chromatography (RP-HPLC) method was developed for the determination of potential impurity, desloratadine in Rupatadine fumarate drug substance and drug product. Chromatographic separation between impurity and Rupatadine achieved on the unisphere C18 (250 x 4.6 x 5μ) column. The mixture of aqueous buffer containing 0.3 M sodium acetate pH 4.4 ± 0.05 (adjusted with glacial acetic acid) and methanol in the ratio of 80:20 % (v/v) respectively. The mobile phase delivered at a flow rate of 1.0 ml/min and the detection was carried out at wavelength 245 nm. The chromatographic resolution between fumaric acid and desloratadine was found to be greater than 5. The response was determined and regression ‘r’ values (correlation coefficient) were obtained greater than 0.998 for related compound and Rupatadine fumarate. The LOQ values for desloratadine and Rupatadine fumarate were 0.25 μg/ml and 0.2 μg/ml respectively. The percentage recovery was found to be 98.0 % to 102.5 % for desloratadine. The drug was subjected to stress conditions as prescribed by ICH guideline. Degradation was fond to occur slightly under oxidative storage condition but drug was stable to acidic and basic hydrolysis, photolysis and thermal storage conditions. The developed method was validated as per ICH guideline.
