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

© 2021 IAALong-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

Microvolumetric droplets in air in hypergravity conditions

The interaction of laser modified medicine solutions with hydrophilic and hydrophobic target surfaces has been investigated under the effect of simulated hypergravity conditions, employing the Large Diameter Centrifuge (LDC) facility, developed by the European Space Agency (ESA). Experiments have been performed within the HyperMed project under the aegis of the ESA “Spin Your Thesis!” 2015 programme. During centrifugation, real-time video files have been recorded regarding generation of ultrapure water, unexposed and laser exposed chlorpromazine aqueous pendant droplets, followed by their detachment due to the exerted high gravitational accelerations and finally by the formation of sessile droplets on target surfaces. In this way, information about the volume of the generated droplet, the degree of wetting and its time evolution at different hypergravity levels has been obtained. Phenothiazine solutions irradiated with UV laser radiation indicate reduced surface tension, thus presenting better wetting properties. Target surfaces impregnated with medicine solutions may constitute an unconventional tool and even vector in developing new drug delivery systems. Such a wetting process under high g-level conditions may be useful in space medicine applications. Microorganisms can survive, grow and even proliferate under the effect of increased gravity. Therefore, upon launching of a spacecraft, during a long-term mission in microgravity conditions, astronauts and spacecraft surfaces may require treatment and decontamination, respectively, against onboard infectious microbes. Since non-terrestrial gravity may alter drug properties, medicine droplets behaviour in interaction with target surfaces under hypergravity conditions is the aim of the present study