Stability problem for space drugs

Two years ago I wrote about the drugs taken on the first lunar landing mission 40 years earlier. The astronauts had access to a number of solid dose medicines, including antibiotics, antinauseants, stimulants, analgesics, hypnotics, decongestants and antidiarrhoeals. The only problem they had was that the packs ballooned in Apollo 11’s low pressure cabin atmosphere because the medicines had been repacked in sealed containers from which the air had not been fully evacuated.

But it has now emerged that space environments may compromise drug stability — a factor that could be significant for drugs stored on permanent space stations in the 21st century, even if it was not a problem on a short 20th century lunar voyage.

The new finding is reported in AAPS Journal, published online by the American Association of Pharmaceutical Scientists. Researchers at the Johnson Space Centre examined the stability of drugs currently taken into space to treat minor illnesses. These drugs are dispensed in special flight-certified containers and stored in compact flight kits.

The research team compared physical and chemical changes in 35 formulations contained in identical kits stowed in identical conditions of temperature and humidity on the International Space Station and on Earth. They found that drugs stored for 28 months in space tended to have a lower active pharmaceutical content than terrestrial controls.

The team suggest that the shorter shelf-life in space may arise directly from exposure to unique environmental factors such as ionising radiation and excessive vibration. A more mundane factor may be the way in which the medicines are repackaged.

The researchers suggest that space-specific degradation products and toxicity limits should be investigated using simulated space environments, including proton and heavy ion radiation, vibration and multiple gravity conditions. The findings would help in developing space-hardy formulations and packaging to ensure that future astronauts can trust their medical kits.