Abstract Flunarizine dihydrochloride is a synthetic compound from the diphenylpiperazine class used for the prophylactic treatment of migraine, vertigo, and peripheral or cerebral vascular disorders. Its physicochemical properties indicate susceptibility to environmental stresses, such as extreme temperature, which may affect the stability and efficacy. Maintaining pharmaceutical stability under environmental stress is crucial in drug development. Despite its clinical importance, limited information exists on the degradation behaviour of the active ingredient under heat or freezing conditions. The aim of the study was to evaluate the thermal stress of flunarizine dihydrochloride and binary mixtures of it with common pharmaceutical excipients, after 24 h of storage at room temperature, 50 °C, and −19 °C. Thermal analyses (TG/DTG) and FTIR-ATR spectroscopy were used to investigate the degradation processes and identify possible structural changes. The results show the influence of storage temperature on stability and emphasise the importance of adequate temperature control to maintain integrity and ensure consistent efficacy and safety in pharmaceutical formulations.
Budiul et al. (Tue,) studied this question.