The results of an opportunistic, pilot-scale study led by Virginia Wotring of the Center for Space Medicine and Department of Pharmacology at Baylor College of Medicine in the U.S. suggest that medication degradation¹ on the International Space Station (ISS) does not differ from what is typically seen on Earth. The study, which used medicine samples sent back to Earth from the ISS, appears in The AAPS Journal, an official journal of the American Association of Pharmaceutical² Scientists, published by Springer. While the ISS is regularly resupplied with medicines to replace those which have passed their expiry date, this may not be possible on exploration missions that travel to more distant points. On Earth, medicines degrade over time, particularly when exposed to light, oxygen, or humidity. Although temperature and humidity conditions on board the ISS are generally within ideal ranges for medicine storage on Earth, until now, there has been little evidence of how medicines might react to factors unique to spaceflight, such as microgravity and constant exposure to elevated radiation levels. 

 

Wotring analyzed³ nine medications which had been stocked on the ISS and returned to Earth unused after 550 days of storage in spaceflight. The medications included sleeping aids, pain relievers, antihistamines/decongestants, an antidiarrhoeal, and an alertness drug. The medicines were returned to Earth and, upon arrival, they were kept under controlled conditions until analysis three-five months later. 

 

The researchers measured the quantity of active ingredients and degradation products present in the medicines. They then used 2012 United States Pharmacopeia (USP) guidelines (which provide clear requirements of the quantity of active ingredients and limits of degradation products allowed in viable⁴ medicines) to determine whether or not the ISS medicines were still viable after being stored in space.

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