Cosmic-ray Irradiation Study of a Space Medicine for Future On-Orbit Manufacturing
posterposted on 14.04.2021, 00:39 by Quy Don Tran, Nigel Spooner, Sean Geoghegan, Jana Stoudemire, Nam Nghiep Tran, Ian Fisk, Volker Hessel
Space medicine and space health is a prerequisite for human space exploration. In space, drug properties are different comparing to Earth. Drugs being carried on space missions have been noticed to have a shorter shelf life relatively compare to Earth counterpart (Zwart et al., 2009). Cosmic radiation is one of the underlying causes of the pharmaceutical instability of space medicine. In this research, we are studying the impact of Earth-simulated ‘space radiation’ on medicines, which are formulated to have higher stability under cosmic radiation. We study the stability of Ibuprofen as a function of its formulation environment, i.e., the pharmaceutical excipients which form a tablet. Ibuprofen is probably the best-studied medicine for its decomposition by irradiation; mostly concerning UV (Caviglioli et al., 2002). Our research is flanked by two running ISS-NASA experiments on a long-duration study of those space medicines under real cosmic irradiation; inside ISS and outside as well. 60 tablet samples were compounded and sent to the International Space Station (ISS) for 6-12 months for experimenting in the real space conditions.
We used varying combinations of pharmaceutical excipient ingredients, which are found abundantly on the moon, such as dicalcium phosphate (CaHPO4), talcum/magnesium silicate (Mg₃Si₄O₁₀(OH)₂), silica (SiO2), titania (TiO2), and iron oxide (Fe2O3). One of our shielding concepts is to coat the tablet with an excipient containing heavy-elemental weight atoms.
First thing is to ensure homogeneity of the distribution of formulation components in our tablet, as the space experiments forced us to work with small specimen sizes and weights (scale of scrutiny). We deliberately formulated each tablet and managed to reduce the Ibuprofen standard deviation from 20% to 5%. For the UV-C radiation investigation, we used a UV lamp with a wavelength of 254 nm. The mild UV-C source does not create detectable damage in about 5.5 hours of exposure. For beta radiation investigation, we used Strontium-90 at effective energy levels ranging from 0.059 to 5.486 MeV. The low linear energy transfer (LET) beta source at 0.1 Gy to 50 Gy does not cause notable damage as well. For alpha particle