Stability of Dosage Forms in the Pharmaceutical Payload Aboard Space Missions

Efficacious pharmaceuticals with adequate shelf lives are essential for successful space medical operations. Stability of pharmaceuticals, therefore, is of paramount importance for assuring the health and wellness of astronauts on future space exploration missions. Unique physical and environmental factors of space missions may contribute to the instability of pharmaceuticals, e.g., radiation, humidity and temperature variations. Degradation of pharmaceutical formulations can result in inadequate efficacy and/or untoward toxic effects, which could compromise astronaut safety and health. Methods: Four identical pharmaceutical payload kits containing 31 medications in different dosage forms (liquid, tablet, capsule, ointment and suppository) were transported to the International Space Station aboard the Space Shuttle (STS-121). One of the 4 kits was stored on the Shuttle and the other 3 were stored on the International Space Station (ISS) for return to Earth at 6-month interval aboard a pre-designated Shuttle flight for each kit. The kit stored on the Shuttle was returned to Earth aboard STS-121 and 2 kits from ISS were returned on STS 117 and STS-122. Results: Analysis of standard physical and chemical parameters of degradation was completed for pharmaceuticals returned by STS-121 after14 days, STS - 117 after11 months and STS 122 after 19 months storage aboard ISS. Analysis of all flight samples along with ground-based matching controls was completed and results were compiled. Conclusion: Evaluation of results from the shuttle (1) and ISS increments (2) indicate that the number of formulations degraded in space increased with duration of storage in space and was higher in space compared to their ground-based counterparts. Rate of degradation for some of the formulations tested was faster in space than on Earth. Additionally, some of the formulations included in the medical kits were unstable, more so in space than on the ground. These results indicate that the space flight environment may adversely affect the shelf life of pharmaceuticals aboard space missions.