Rapid quantitative determination of related substances and degradants in milnacipran

A simple, sensitive, precise and accurate stability-indicating ultra-performance liquid chromatography (UPLC) method was developed for the quantitative determination of the purity of the active pharmaceutical ingredient of milnacipran hydrochloride (MCP) and its pharmaceutical dosage form in the presence of its process-related impurities and degradation products. The proposed UPLC method utilizes Acquity UPLC BEH 100 mm, 2.1 mm and 1.7 µm phenyl columns at 27°C with a gradient program of 12.0 min at a flow rate of 0.5 mL/min. The compounds of interest were monitored at 210 nm. The resolution for MCP and 12 (potential byproducts and degradation) impurities was found to be greater than 2.0 for any pair of components. The high correlation coefficients (r(2) >0.9995) indicate clear correlations between the concentrations of investigated compounds and their peak areas. The relative standard deviations obtained for the repeatability and intermediate precision experiments were less than 5.0%. The accuracy of the method was further ascertained by performing recovery studies through spiking experiments. The drug substance was subjected to hydrolytic, oxidative, photolytic and thermal stress conditions, as per the International Conference on Harmonization (ICH). The developed method was validated according to the current ICH guidelines for specificity, limits of detection and quantitation, linearity, accuracy, precision, ruggedness and robustness. The method is also suitable for the assay determination of MCP in pharmaceutical dosage forms.