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Tablets with Increased Aroma Have Better Stability in Space

After returning from their trip into space, tablets subjected to the harsh effects of cosmic radiation have shown some unexpected results: those with increased aroma were not degraded as much as those with less taste.

"Medicines taken on space missions are exposed to cosmic rays which limit their 'space shelf life' and can even lead to the formation of toxic substances as the drug content declines," said the University of Adelaide's Professor Volker Hessel, Research Director of the Andy Thomas Centre for Space Resources and Professor in the School of Chemical Engineering and Advanced Materials, who led the project to send tablets into space.

"We have tested and proven countermeasures to the degrading effects of cosmic rays by sending ibuprofen tablets made in our laboratory to the International Space Station (ISS) for six months and checking them on their return.

"Four of the six ibuprofen tablets from outside the ISS, each made with a distinct formulation and protection concept, significantly decomposed to a high number of ibuprofen fragments. The tablet with highest iron oxide content in the coating showed only minor ibuprofen loss."

A coating of iron oxide was formed under the pressure of compacting the tablets during manufacturing in the lab.

"But to our surprise, natural aroma enhancers, which were added to the tablets by our research partners from the University of Nottingham's International Flavour Research Centre led by Professor Ian Fisk, seemed to help stabilise the ibuprofen even when no large iron oxide content was present," said Professor Hessel.

"While this result needs further investigation and verification, one might guess that the radical scavenging nature of the aroma molecules – terpenes and alkyl-phenols with reactive chemical bonds – might cause this effect." 

Terpenes and alkyl-phenols are naturally occurring chemical compounds found in plants and some animals. 

The team developed special tablet formulations of the anti-inflammatory drug that include solid and dense drug packing which protected the drug from damage by some of the cosmic radiation. They also modified the chemical nature of ibuprofen by complex formation of the drug with the excipients, resulting in a 'stronger' ibuprofen. Excipients are substances that are included in a tablet in addition to the drug component that has a variety of uses assisting the manufacturing process or enhancing the stability of the drug.

The tablets were sent to the ISS for six months in a partnership between the University and space technology companies Space Tango and Aegis Technologies. One batch of 60 tablets was carried inside the space station and one batch of six tablets was outside the station in the Materials International Space Station Experiment (MISSE) platform. They were exposed to one of the harshest environments known.

When they returned from their epic journey the space tablets were compared to a control batch of tablets left on Earth.

"The results from sending tablets to the ISS shows that experiments carried out in space can provide insights for improving manufacturing on Earth," said Professor Hessel.

University of Adelaide researchers are continuing their investigations in the lab by using different radiation sources to test the effect of them on pure ibuprofen on its own as well as inside tablets.

"High energised photon radiation – synonymous with the cosmos' gamma radiation – is likely to be the biggest threat to medicines in space as it's been found to penetrate the tablets and destroy the ibuprofen," he said.


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