Evaluation of Haloperidol Photodegradability and Elucidation of Chemical Structure of Its Photoproduct

Haloperidol (HP) is a typical antipsychotic drug, which is used for the treatment of psychosis including schizophrenia. In this study, HP photodegradation was evaluated to clarify the photostability of HP tablets because the photodegradation might affect both the quality and the quantity. For the better understanding of photochemical properties of HP, firstly, residual amounts of UV-irradiated HP samples were monitored using a high-performance liquid chromatography (HPLC) system. HP was photodegraded along with the generation of several photoproducts, so structural elucidation of them was carried out based on electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). The authors succeeded in elucidating the chemical structure of one photoproduct and its generation pathway. Furthermore, in silico toxicity prediction was performed to predict the toxicological potencies of the photoproduct. Finally, the photostability evaluation of HP tablets and its altered forms (powders and suspensions) were evaluated.