A study led by Duke Health found that over half of the medications stocked in space, including pain relievers, antibiotics, allergy medicines, and sleep aids, would expire before astronauts return to Earth.

Astronauts could potentially rely on ineffective or even harmful drugs, according to the study published on July 3 in npj Microgravity, a Nature journal.

"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," said senior study author Daniel Buckland, M.D., Ph.D., an assistant professor of emergency medicine at Duke University School of Medicine and an aerospace medicine researcher.

Expired medications can lose their potency to varying degrees. The stability and effectiveness of medications in space compared to Earth are still largely unknown. The harsh environment in space, including radiation, might reduce the effectiveness of medications.

Buckland and co-author Thomas E. Diaz, a pharmacy resident at The Johns Hopkins Hospital, indicated that expired medications could be a significant challenge as space agencies plan for longer missions to Mars and beyond.

Diaz used a Freedom of Information Act request to get information about the space station's medication inventory, assuming NASA would use similar drugs for a Mars mission.

The researchers used an international drug expiration date database and found that 54 of the 91 medications had a shelf-life of 36 months or less.

Even with optimistic estimates, about 60% of these medications would expire before a Mars mission ends. More conservative estimates suggest this figure could rise to 98%.

The study did not account for accelerated degradation but focused on the issue of not being able to resupply a Mars mission with newer medications. This lack of resupply affects not only medications but also other critical supplies, like food.

Increasing the number of medications brought on board could help offset the reduced efficacy of expired drugs, the authors suggested.

"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 three years, select medications with longer shelf-lives, or accept the elevated risk associated with administering expired medication," Diaz said.

"Prior experience and research show astronauts do get ill on the International Space Station, 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," Buckland added.

Additional authors include Emma Ives and Diana I. Lazare. The study received no external funding.

Research Report:Expiration analysis of the International Space Station formulary for exploration mission planning

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