Drugs intended to treat minor illnesses of astronauts in space may need special handling to remain stable in the environment of space, NASA scientists say.

Researchers at the Johnson Space Center in Houston, writing in the AAPS Journal, suggest that some of the pharmaceuticals stored on space flights may have shorter shelf-life than they do on Earth.

They compared physical and chemical changes in 35 formulations in identical pharmaceutical kits stowed on the International Space Station and on Earth, and found that after 28 months of stowage in space medications from each flight kit had a lower active pharmaceutical content than the same pharmaceuticals kept on the ground.

"It is important to characterize space-specific degradation products and toxicity limits using ground-based analogue environments of space that include proton and heavy ion radiation, vibration and multiple gravity conditions," the researchers wrote.

"This information can facilitate research for the development of space-hardy pharmaceuticals and packaging technologies."