Imagine a trip home after 2 months away, only to realise when you arrive that you cannot sit up or stand—this was the experience of National Aeronautics and Space Administration (NASA) astronaut, Garret Reisman, who reports taking 15 minutes to be able sit up once entering Earth's gravity after space shuttle missions, and another 15 minutes to stand (Wattles, 2020). On 2 August, NASA astronauts, Bob Behnken and Doug Hurley, made their safe but jarring return to Earth, splashing down in the Gulf of Mexico at the end of a 19-hour journey home in SpaceX's Crew Dragon capsule after 2 months in the zero gravity environment of the International Space Station (Sputnik, 2020).
How space affects people
Being in space not only affects the ability of humans to adjust to sitting or standing in gravity when they return, but it also affects their bone density, muscle mass and stress hormone levels, as well as their cardiovascular and respiratory systems (Tatum, 2020).
When bones and skeletal muscles no longer need to carry the weight of the body in zero gravity, they begin to lose their mass (Tatum, 2020). Blood and fluids usually needed in the lower body are redistributed in space to the upper body, decreasing the plasma volume and heart size (Tatum, 2020). All body systems are affected when humans are exposed to the microgravity of space; in fact, even the immune system becomes less active (Tatum, 2020).
The effects on humans of spending long stretches of time in zero gravity need to be addressed. For example, the negative impact on bone density can be combatted using treatments approved for osteoporosis (Tatum, 2020). The only problem is, not only are humans affected by zero gravity but so are medications (Tatum, 2020).
How space affects drugs
According to the Dose Tracker experiment that looked into drug consumption on the International Space Station, each crew member took an average of four medications per week, mostly consisting of analgesics, decongestants and sleep aids (Wotring, 2015; Tatum, 2020). However, the environment in space, the low humidity and radiation aboard spacecraft and the repackaging of medications to be able to store them on missions all appear to play their part in reducing the shelf-life of the treatments that astronauts require (Gallagher, 2011). In addition, the physiological changes the body undergoes and the changes that take place within drugs while in space are expected to result in altered interactions between the body and any administered medications (NASA, 2020).
Creating drugs for deep space
There are several potential solutions being explored to solve this issue. Regular resupply missions take place to replenish food, water, equipment and medications to the International Space Station, only 400 km away from the Earth (Tatum, 2020). However, plans to take manned spacecraft to the moon and to Mars in coming years require new solutions, as spacecraft and crew will then be 225 million km away, which is much too far away for resupply missions to be feasible (Tatum, 2020). In fact, ‘pharmacies’ aboard the spacecraft will need to be stocked up with years' worth of supplies, and work is ongoing, mainly at the proof-of-concept stage, to make this possible.
While the 3D printing of drugs aboard spacecraft has been considered, the machines required are too large to fit, particularly aboard the small spacecraft that are expected to take astronauts to Mars (Tatum, 2020). One of the potentially more promising solutions is a synthetic biology approach, in which natural products, such as lettuce, for example, can be genetically modified to produce medicines by either shooting DNA into them using a gene gun or infecting the plants with genetically modified viruses that could replicate quickly enough to produce the necessary ingredients but that are not transmissible to humans (Tatum, 2020).
Microgravity ‘terrestrial’ drug development
Interestingly, not only are treatments for use in deep space being explored on Earth, but treatments for use on Earth have also been developed in the microgravity environment of the International Space Station.
For example, the process of microencapsulation, whereby liquid-filled micro-balloons that are biodegradable hold drugs in order for them to be delivered to specific treatment sites in patients with cancer, was developed on board the International Space Station making use of its microgravity environment (Tatum, 2020). This environment also holds the ability to speed up drug development, as it did for vaccinations such as those against Salmonella and methicillin-resistant Staphylococcus aureus (MRSA) (Tatum, 2020). Lastly, crystals formed in space have fewer imperfections than those developed on Earth, a process believed to hold the potential to speed up drug development on Earth (Tatum, 2020).
Much research is in its early stages, but it is clear that gravity, and zero-gravity, have interesting effects on both the human body and the development of future treatments. Research in space has hopeful implications for novel treatments being developed for use on Earth, and research on Earth is ongoing to determine the best ways to look after astronauts, and help them hit peak performance, as they take off to the deep space in the years ahead.