The research by NASA`s Johnson Space Center found that the peculiar conditions away from the earth, including weaker gravity and higher radiation, could be the reason behind drugs losing their effectiveness, the Daily Mail reported.
On Earth, drugs are designed to be stored for a couple of years since manufacturing date. But they are required to be kept in precise conditions, such as away from direct sunlight or in a cool and dry space, to retain their effectiveness.
As longer space missions have increased the need for astronauts to take medicines, NASA scientists wanted to know whether space`s unique environment - including radiation, vibrations, microgravity, a carbon dioxide-rich environment and variations in humidity and temperature - affected drugs` effectiveness.
To investigate this, four boxes of drugs, containing 35 different medications, were flown to the International Space Station (ISS), while 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 scientists found that a number of drugs lost their effectiveness after their voyage to the ISS.
They 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."