Hydrogel can preserve medications for weeks outside of a fridge

Many medications must be refrigerated or they lose their effectiveness, but a new method of packing protein-based drugs into a stiff gel could make them last longer at room temperature.

Drugs can break down if they aren’t stored properly, which can make them unsafe to use. Exposure to high temperatures, for example, can break the chemical bonds that maintain a drug molecule’s shape, disrupting its function. For some drugs, shaking can make their molecules clump together, reducing their efficacy. Matthew Gibson at the University of Manchester in the UK has been working on addressing these challenges for almost 15 years.

He and his colleagues have now developed a method that could make handling protein-based drugs simpler and more practical. He says the new advance came from working with Dave Adams at the University of Glasgow in Scotland, who specialises in making hydrogels. They worked out how to mix proteins with gel ingredients and end up with a stiff white structure that can be loaded into a syringe. In this form, proteins that would usually have to be refrigerated at -20°C (-4°F) withstood temperatures as high as 50°C (122°F) and remained functioning under these conditions for up to four weeks.

The hydrogel gets its stiffness from small molecules combined into large chains, which are then broken by applying force. In syringes, pushing down on the plunger breaks the molecular bonds, turning the gel and protein mixture into a liquid. The hydrogel remnants were too big to enter the syringe’s needle, so only the drug leaves the syringe.

The team tested this method with several compounds, including bovine insulin and β-Galactosidase, an enzyme commonly used for gene studies in biology. They also mailed a box filled with containers full of protein-packed hydrogels to themselves and found that the proteins withstood the temperatures and jostling of the journey through the postage system.

Though there are laboratory methods that can keep proteins stable for longer, this approach may be better suited to leave the lab and enter the clinic, says Alex Brogan at King’s College London. He says that it would most benefit countries and regions where cold storage is rare and prohibitively expensive. If the new method works with protein-based vaccines, it could make disease prevention more equitable, he says.

Gibson says that he and his team are confident they could make their hydrogel at industrial scales, but they want to conduct more studies on its longevity and safety. While using it with vaccines is on their wish list, in the short term the method could also be used to store, transport and administer semaglutide, a drug used to treat diabetes and obesity.