This would be huge for pharmacy if/when it all gets worked out and commercialized. Eliminating cold chain? Wow.
Kaplan’s process to formulate drugs with silk is incredibly simple. After preparing a solution of silk protein in water, the medicines are added and the mixture is freeze-dried to create a stable preservative matrix. Kaplan explains that the silk protein is generally quite hydrophobic and forms strong stabilising interactions with molecules embedded in it. ‘Coupled with the ability to process silk just in water at ambient conditions means you can put sensitive molecules in there and not lose their function,’ he adds.
The group prepared films of silk containing the combined measles, mumps and rubella (MMR) vaccine and showed that it can be stored for six months at 45°C and retain more than 85% of its activity, compared to powdered forms that degraded in a few weeks.
Silk films impregnated with the antibiotic tetracycline also lasted longer than solutions, but an unexpected result was that the silk also seemed to stabilise the antibiotic against degradation by light. ‘Tetracycline is inherently light-sensitive,’ says Kaplan, ‘and we noticed that the films weren’t changing colour at the same rate as the solutions [when they were stored in the light].’ He explains that the stabilisation mechanism is unclear – the silk is transparent, so it’s not just that it’s physically blocking the light out. ‘We assume it’s the same reason we see the other stabilisation effects,’ he says, ‘but we need to probe that further.’
An abstract of the article can be found online at the Proceedings of the National Academy of Scinces website.(10.173/pnas.1206210109)