Access to medical supplies is a major concern for astronauts. Difficulty sleeping, pain, congestion, and allergies are common complaints from extraterrestrial missionaries.
Drug use by US crew members aboard the International Space Station (ISS) was tracked between 2002 and 2012. And according to the data, astronauts used sleeping pills more often. 10 times that of people on earth. They also use ibuprofen to relieve pain caused by pressure changes in the space, higher carbon dioxide levels, and joint problems. Unfortunately, the longer the spaceflight, the higher the likelihood of acute illness. Common astronaut health problems include a weakened immune system, bone calcifications, and low blood pressure.
On Earth, most drugs expire within a year. In space, it could be earlier unless protected by controlled conditions on the ISS.
To find out how to extend the life of drugs in space, Dr Volker Hessel of the University of Adelaide led a team that launched popular drugs into space. One of the goals was to understand how space radiation might affect ibuprofen. ISS astronauts placed six pellets in the MISSE (International Space Station Experimental Material) experiment. Essentially MISSE consists of four suitcase-sized containers located outside the ISS. Inside are materials ready to endure the harsh conditions of space, unprotected.
Commercial ibuprofen tablets are full of other materials called “excipients” that encapsulate the active ingredient. Drug manufacturers add these chemicals to make the pill palatable or improve absorption into the body. In space, some of these excipients protect ibuprofen from breaking down.
Volker says that after a year, only two out of six ibuprofen tablets retain their physical and chemical properties. And they may have clues to make more durable drugs.
Volker and his team coated their pellets with a layer of iron oxide. Due to its high density, iron oxide can block gamma radiation. Therefore, the team hopes that the coating will provide some protection. However, they did not expect that some artificial flavoring chemicals could also help preserve ibuprofen tablets.
Each tablet tested contained a mixture of three excipients: acetic acid flavor, malty biscuit flavor 037, and 4-ethyl phenol wine flavor. Malty-biscuity 037 has a rather pleasant taste and is produced by maturing malt. Tasters describe 4-ethylphenol as drug or horse.
Volker says the chemical structure of two of these additives may explain why they help ibuprofen last longer in space. “They basically shut down the basic functional groups… Each of the three flavors has a different mechanism for doing this,” explains Volker.
Malty-biscuit contains myrcene, which is a terpene. Meanwhile, 4-ethylphenol has a methylene group. Volker says the structure of these two groups makes them free radical scavengers. One type of radiation, beta radiation, involves high-energy electrons. They can collide with molecules, breaking atomic bonds. These molecules become free radicals, which can react with other molecules. This causes a chain reaction that can quickly break a pill.
Free radical scavengers can limit damage by stabilizing free radicals. This slows down the breakdown of ibuprofen. After a year in space, the tablets were returned to Earth. While the free radical scavenger hypothesis may explain what happened, Volker’s team has yet to test it. It involves separating the molecules in the tablet by size and identifying them one by one. Once they figure out how the pills break down, they can get a clearer picture of what happened.
This could help create more durable drugs for space exploration. With NASA planning to send humans to Mars by the 2040s, astronauts will need drugs that can prolong the trip. “We really believe in human space exploration,” says Volker. “For supply chains and habitats in space, [long-term drugs] are part of the concept.”
- The project to create more durable space drugs
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