Development of the Validated Stability-Indicating Method for the Determination of Vortioxetine in Bulk and Pharmaceutical Formulation by HPLC-DAD, Stress Degradation Kinetics Studies and Detection of Degradation Products by LC-ESI-QTOF-MS

Vortioxetine (VOR) is a new antidepressant drug used to treat major depressive disorder. In this work, a novel, simple, rapid, accurate, precise, selective, stability-indicating, and fully validated high-performance liquid chromatography method with diode array detection (HPLC-DAD) was developed to determine VOR in bulk and pharmaceutical formulations. A Polar-RP column was used, with a mobile phase consisting of acetonitrile (ACN), methanol (MeOH), acetate buffer pH 3.5, and addition of diethylamine (DEA) in the isocratic elution mode. Assessing the stability of the VOR is fundamental to guarantee the efficacy, safety, and quality of drug products. In this study, the VOR active pharmaceutical ingredient (API) and tablets were subjected to a detailed study of forced degradation, using several degrading agents (acid, alkaline, water, heat, light, and oxidation agents). The developed HPLC-DAD method allows the collection of all the essential data to determine degradation kinetics. It was found that the decomposition of vortioxetine is fragile towards oxidative conditions and photolysis, yielding the first-order and second-order kinetic reaction in the above stress conditions, respectively. The degradation products (DPs) were identified by the high-resolution liquid chromatography coupled with electrospray ionization-quadrupole-time of flight-mass spectrometry (LC-ESI-QTOF-MS) method. The HPLC-DAD method was successfully applied for the quantification of VOR in tablets. Additionally, in silico toxicity prediction of the DPs was performed.