Photoactive chlorpromazine and promazine drugs exposed to hypergravity conditions after interaction with UV laser radiation

Abstract

Long-term space missions must be prepared to provide means to treat astronauts' illnesses that could occur at take-off, during flights or arriving on other planets. This could be achieved using multipurpose medicines. Phenothiazine derivatives, normally used to treat mental and emotional disorders, are photosensitive drugs and in solutions undergo molecular modifications by exposure to UV laser radiation, which leads to transformation of a parent-compound into photoproducts with increased antimicrobial activity when compared to unirradiated solutions. Since space missions involve, even if only for short durations, hypergravity environment transitions, their effects on unirradiated and laser irradiated chlorpromazine and promazine aqueous solutions were studied in this paper. The experiment was performed at the European Space Agency's Large Diameter Centrifuge, subjecting solutions at 20 times Earth's gravitational acceleration. Since, generally, little is known about medicines exposed to high-g levels, this research brings an insight into the impact of hypergravity on phenothiazines. To evaluate drug stability, samples were assessed pre- and post-hypergravity treatment by pH measurements, UV-Vis-NIR/FTIR spectroscopy and thin layer chromatography. No significant changes between uncentrifuged and centrifuged samples were evidenced subsequent to hypergravity exposure, emphasising the stability of unirradiated and laser irradiated phenothiazines, which may allow their use during future space missions.