Pilot degradation study of gamma irradiated ciprofloxacin in its primary packaging material for space pharmaceutical applications

Ensuring the stability of pharmaceuticals is crucial for astronaut health and mission success during long-duration spaceflight. Space radiation can penetrate spacecraft shielding and compromise the stability of drugs, yet literature on such effects remains limited. Ground-based simulations thus offer critical insights about how pharmaceuticals behave in extreme space environment. The present preliminary comparative study investigated the impact of gamma and photolytic irradiation on the stability of ciprofloxacin, a key antibiotic in the ISS formulary. The study was carried out on ciprofloxacin API solutions, solid API, and both solid and liquid formulations, with and without primary packaging material. The results of physical evaluation showed dose-dependent color changes from colorless to brown in API solutions (100 ppm and 3,000 ppm) as well as liquid formulations without primary packaging material. The XRD analysis of API powder revealed loss of crystallinity at 400 Gy gamma dose. Chemical stability of each irradiated sample checked using high performance liquid chromatographic method. A comparative degradation profile of photo irradiated and gamma irradiated samples of ciprofloxacin revealed the significant difference. Degradation products, CIP1 and CIP2 were observed only in gamma irradiated samples while CIP6 was observed after photo irradiation. The identification of degradation products was carried out using LC–MS/MS and based on their fragmentation patterns, plausible degradation pathways were proposed. This is the first report to show that the primary packaging material used for ciprofloxacin eye/ear drops could not control the degradation on exposure to gamma rays.