Study of Forced Degradation Behavior of Amisulpride by LC-MS and NMR and Development of a Stability-Indicating Method

Introduction: A simple, isocratic High Performance Liquid Chromatography (HPLC) method has been modified for the qualitative and quantitative analyses of amisulpride related substances. This method is based on using of RP-C8 (250 4.6 mm) column and a mixture of phosphate buffer and methanol as mobile phase. Materials and Methods: Various forced degradation studies were conducted to establish an impurity profile for amisulpride raw material and in the tablet formula. Four degradation products were produced upon exposing amisulpride to different degradation conditions (acidic, basic, oxidative, photolytic, aqueous and thermal); three of them were already identified by British Pharmacopeia (BP). Conclusion: The fourth new significant degradant was observed only under acidic degradation of amisulpride (4 ml of 4 M hydrochloric acid solution at 70 °C for 5 hrs). Its structure was characterized using LC-MS and NMR (1H NMR, 13C NMR and DEPT) techniques. Excipient components, examined in this study, have no effect towards producing any extra new degradation products.