Research

Case studies

Microneedles


Professor Ryan Donnelly, School of Pharmacy

Premature babies are often on lots of drugs to keep them alive, so how do we know what concentration to give without causing side effects?

Ryan Donnelly joined the School of Pharmacy in January 2004. “I am keenly interested in enhancing the quality of life of patients through designing enhanced drug delivery systems.”

The microneedles being developed by him and his team are about the size of a postage stamp, the surface covered with almost invisible pin-points. They’re tiny but their potential is huge. Ryan explains, “These micro-structures painlessly penetrate the skin. They’re so small that they don’t cause any bleeding and they don’t stimulate any nerves. Most drug substances don’t cross the skin easily. With our microneedles we can bypass the barrier that the skin provides and deliver a drug of any size, as long as it’s soluble in water.”

The project has received much support as a means of drug delivery. But the research for EPSRC has a different objective, not delivery, but extraction.

“We realised that there could be another application. The concentration of drug substances in the blood is in equilibrium with that of the fluid in the skin. So our idea is to place a microneedle which swells and provides a conduit. Then we can insert a special type of probe which will detect drug substances. It’s a way of blood-free monitoring.”

He has examples of how this can be applied. “Premature babies are often on lots of drugs to keep them alive. But we don’t know how fully developed their organs are. So how do we know what concentration to give without causing side effects? Heel prick samples are the usual method of taking blood. But these are very limited volumes and you can’t do it too often without causing trauma, bruising or scarring. Using a microneedle patch, you can take samples continuously over a day to work out what’s going on and in a minimally-invasive, blood-free fashion.”

Another example is how to detect whether a driver who has been stopped by the police and has passed a breathalyser test has been taking drugs. “And there is the developing world where a patient may have HIV/Aids and so taking blood samples may be difficult. Microneedles could eliminate a lot of the risk.”

Ryan praises the collaboration of colleagues Colin McCoy, David Jones and Stephen Bell. The project began in July 2010 and will run until 2013. “It’s at an early stage but the amount of industrial interest already just shows the possibilities it has.”