Since Tim Peake became the first British astronaut to go to the International Space Station, there has been a huge resurgence of interest in life in space. Although highly trained and very fit, astronauts will still occasionally need medicines and of course there is the possibility that at some point a medical emergency will occur in space. To address this, the space station keeps supplies of medicines and the necessary equipment. So how does being in space affect medicines?
On earth, medicines are tested during their development to assess the effects of, for example, temperature, moisture, oxygen and light on their stability, and are packaged and stored to ensure they remain stable and effective over their shelf life. The temperature and humidity conditions used to test the stability of medicines reflect the conditions the medicines undergo during transport and storage in different parts of the world.
In the artificial environment in the International Space Station temperature and humidity are closely controlled. However, storing medicines in space will result in their exposure to further stresses such as radiation, vibration and weightlessness which may have an impact on how stable the medicines can be.
Changes in gravity can have adverse effects on the stability of pharmaceutical emulsions, creams and suspensions, and vibration can cause segregation in powders. And while radiation is used to sterilise some types of injection and medical devices, it can cause detrimental effects to medicines and packaging depending on the dose used. A further complication is that medicines transported to the space station may be repackaged into containers that may not provide adequate protection from moisture, oxygen and light.
A study published in 2011* found that a higher percentage of medicines stored in space had a lower drug content than those stored back on earth. It was considered that exposure to low dose ionisation radiation and the repackaging of medicines may have had an adverse effect on the stability of the medicines.
However, one potential benefit of keeping medicines on the International Space Station is that the carbon dioxide rich environment may help minimise the degradation of medicines prone to oxidation such as vitamin C and Vitamin A.
Whilst humans continue to investigate space they need the best medicines they can get. Further research by pharmacists and others into the formulation, stability and packaging of medicines that will be transported to space could help ensure astronauts get the same quality of medicines as people on earth.
* (Du B, et al. Evaluation of physical and chemical changes in pharmaceuticals flown on space missions. The AAPS Journal 2011; 13(2): 299-308)