Hydrogel can preserve drugs for weeks outside the refrigerator

Many medicines need to be kept refrigerated or they become ineffective, but a new way of packaging protein-based drugs into a stiff gel could potentially extend their shelf life at room temperature.

If drugs are not stored properly, they can break down and become unsafe to use. For example, exposure to high temperatures can break down the chemical bonds that hold a drug’s molecules in place, impairing their function. Shaking some drugs can cause the molecules to clump together, reducing their effectiveness. Matthew Gibson of the University of Manchester in the UK has been working to solve these challenges for almost 15 years.

He and his colleagues have developed a way to make working with protein-based drugs simpler and more practical. He says the new advancement came from a collaboration with Dave Adams of the University of Glasgow in Scotland, who specializes in making hydrogels. They figured out how to mix the proteins with gel components into a hard, white structure that can be packed into a syringe. In this form, the proteins, which normally must be kept refrigerated at -20°C (-4°F), could survive temperatures as high as 50°C (122°F) and remained functional under these conditions for up to four weeks.

Hydrogels get their stiffness from small molecules bound together in large chains that break when force is applied. In a syringe, pushing down on the plunger breaks the molecular bonds, turning the gel-protein mixture into a liquid. The hydrogel remains too large to fit through the needle, so only the drug comes out.

The team tested the method with several compounds, including bovine insulin and beta-galactosidase, an enzyme commonly used in genetic biology, and mailed themselves boxes filled with tubs of hydrogel packed with the proteins, finding that the proteins could withstand the temperature and jolts that come with going through the postal system.

While there are laboratory methods that can keep proteins stable for longer periods, this method may be suitable for moving out of the lab and into the clinic, says Alex Brogan of King’s College London. He says this would be particularly useful in countries and regions where refrigeration is rare or cost-prohibitive. If the new method works for protein-based vaccines, he says it could make disease prevention more equitable.

Gibson says he and his team are confident they can produce the hydrogel on an industrial scale, but want to study its longevity and safety further. Using it in a vaccine is on their wish list, but in the short term the method could also be used to store, transport and administer the diabetes and obesity drug semaglutide.