BBC News reports scientists have discovered that the effectiveness of drugs declines much more rapidly in space than on Earth:
Four boxes of drugs, containing 35 different medications, were flown to the International Space Station.
Four identical boxes were kept in controlled conditions at the Johnson Space Center.
The boxes came back to Earth after varying lengths of time in space. One was there for just 13 days, whereas another spent 28 months on the space station.
The study concluded: "A number of formulations tested had a lower potency after storage in space with consistently higher numbers of formulations failing United States Pharmacopeia potency requirement after each storage period interval in space than on Earth.
"This reduction in potency of flight samples occurred sooner than the labelled expiration date for many formulations suggesting that storage conditions unique to the spacecraft environment may influence stability of pharmaceuticals in space".