Evaluation of degradation profile of selected space medicine after accelerated gamma irradiation and its comparison with photodegradation as per ICH Q1(B)

Long-duration space missions requires, the stability of pharmaceuticals for maintaining astronaut health. Pharmaceuticals are exposed to a unique space radiation environment that alters their stability and efficacy during prolonged missions. Gamma radiation is one of the major radiation present in space and it can penetrate spacecraft and affect the stability of pharmaceuticals by inducing physical or chemical changes. To evaluate the effect of gamma radiation on the physical and chemical stability, two drugs were selected namely ciprofloxacin and promethazine with its marketed liquid formulations. Both were exposed to gamma and photo radiation in the present study. Gamma irradiation was carried out at varying doses from 25 Gy to 800 Gy and photo irradiation was conducted over 1.2 million lux hours as per ICH Q1(B) guideline. The chemical stability of the exposed samples was analyzed using RP-HPLC analysis. Ciprofloxacin and Promethazine aqueous API solution and formulations exhibited dose-dependent degradation on gamma exposure. Comparative degradation profile of photo and gamma-irradiated aqueous solution of ciprofloxacin and promethazine indicates the difference in the degradation pathways leading to the formation of degradation products. Significant degradation was observed in the liquid formulation of ciprofloxacin with and without packing on gamma exposure. This is the first report to show that the primary packaging material used for ciprofloxacin eye/ear drops enables to control the degradation after irradiation with a low dose of gamma rays.