Ground-based selected ionizing space radiation effects on stability of APIs and their formulations

Primary goal of any space mission is to keep astronauts healthy and fit during entire mission. One of the important challenges for that is providing a safe and effective pharmacy with the capabilities to address both scheduled and unanticipated medical conditions that may arise during spaceflight. Extended exposure to space environmental conditions may trigger drug deterioration, impacting quality, effectiveness, and safety. To assess the influence of space ionizing radiations on the stability of medicines launched aboard spacecraft, a preliminary ground-based ionizing radiation drug interaction study was carried out at different doses in the present work. Four different types of radiations - proton, neutron (thermal, fast), gamma and heavy ions (⁵⁶Fe) were used to irradiate selected drugs namely diclofenac, ciprofloxacin and metoprolol along with their formulations. Chemical stability of each irradiated sample was checked using high performance liquid chromatographic method. Significant degradation was observed in even solid-state during proton irradiation in both Active Pharmaceutical Ingredient (API) and tablet dosage form. Solution of active pharmaceutical ingredient and liquid dosage forms were prone to degradation in presence of gamma radiation. No physical and chemical changes observed after neutron and ⁵⁶Fe irradiation. Irradiation of the same drug with different radiations demonstrated varying HPLC chromatographic profiles in terms of %degradation as well as proportion of same degradation products. This indicates possibility of different degradation pathways to generate degradation products.