Expiring medicines will challenge crewed Mars missions

Space agencies need to add expired medicine to the list of perils associated with long-term space travel.

New research suggests that more than half of the medicines stocked on the International Space Station (ISS) would expire before astronauts could return from a multi-year mission to Mars.

According to the study, published in the Nature journal npj Microgravity, astronauts might have to resort to relying on ineffective or even harmful drugs before the end of the 3-year journey.

“It doesn’t necessarily mean the medicines won’t work, but in the same way you shouldn’t take expired medications you have lying around at home, space exploration agencies will need to plan on expired medications being less effective,” says senior author Daniel Buckland, aerospace medicine researcher and assistant professor of emergency medicine at Duke University in the US.

Co-author Thomas Diaz, a pharmacy resident at The Johns Hopkins Hospital in the US, used a Freedom of Information Act Request to obtain information about the medicines stocked on the ISS.

“Prior experience and research show astronauts do get ill on the ISS, but there is real-time communication with the ground and a well-stocked pharmacy that is regularly resupplied, which prevents small injuries or minor illnesses from turning into issues that affect the mission,” says Buckland.  

The assumption is that NASA would use similar medications for a Mars mission. However, unlike on the ISS, such a mission couldn’t resupply.

Using a database of international drug expiration dates, the researchers determined that 54 of the 91 medications used on the ISS have a shelf life of 36 months or less.  

They estimate that about 60% of these medications, or 98% under more conservative assumptions, would expire before the end of a Mars mission.

Because we understand little about the effects of spaceflight on the stability and potency of medications, the researchers didn’t consider possible accelerated degradation from prolonged exposure to the space radiation environment.

The authors say increasing the number of medications brought on board could help compensate for lowered efficacy of expired medications.

“Those responsible for the health of space flight crews will have to find ways to extend the expiration of medications to complete a Mars mission duration of 3 years, select medications with longer shelf-lives, or accept the elevated risk associated with administering expired medication,” says Diaz.