Skin patch releases drugs when stretched

A wearable drug delivery device has been developed which can release drugs when the patch is stretched

The strain-triggered, drug delivery device has been developed by researchers at North Carolina State University and the University of North Carolina at Chapel Hill.

According to NC State, the technology consists of an elastic film that is studded with biocompatible microcapsules. These microcapsules are packed with nanoparticles that can be filled with drugs.

The university said in a statement that the microcapsules stick halfway out of the film on the side of the film that touches a patient’s skin.

The drugs release slowly from the nanoparticles and are stored in the microcapsules.

When the elastic film is stretched it also stretches the microcapsules – enlarging the surface area of the microcapsule and effectively squeezing some of the stored drug out onto the patient’s skin, where it can be absorbed.

Yong Zhu, co-senior author of a paper describing the work and an associate professor of mechanical and aerospace engineering at NC State, said: “When the microcapsule is stretched from left to right, it is also compressed from bottom to top. That compression helps push the drug out of the microcapsule.”

After being stretched the microcapsule is refilled by the drugs that continue to leak out of the nanoparticles.

Zhen Gu, co-senior author of the paper and an assistant professor in the joint biomedical engineering program at NC State and UNC-Chapel Hill, said: “This could be used to release painkillers whenever a patient with arthritic knees goes for a walk, or to release antibacterial drugs gradually as people move around over the course of a day.”

Jin Di, co-lead author and a PhD student in Gu’s lab, said: “This can be used to apply drugs directly to sites on the skin, such as applying anti-cancer medications to melanomas or applying growth factors and antibiotics for wound healing.”

The researchers are also said to have incorporated microneedles into the system, applying them on top of the microcapsules.

The microneedles are small enough to be painless, but large enough to allow drugs to diffuse into the bloodstream through tiny capillaries underneath the skin.