A heat-activated pump helps microneedle-based systems deliver drugs through the skin.

Providing a pain-free alternative to the traditional hypodermic needle, transdermal drug delivery has a fairly successful track record in effectively delivering pharmaceutical agents—perhaps best represented by the nicotine patch that helps smokers kick their addiction. But expansion of the pain-free patch method is hindered by its inability to deliver large-molecule drugs through the skin. A novel pump created by researchers at Purdue University (West Lafayette, IN), however, could help to overcome this obstacle.

As researchers worldwide explore the use of microneedle arrays as the driver of drug-delivery patches, the problem persists as to how to effectively deliver the drugs through the skin. Pumps are required; however, existing pumps on the market are not suited for use on patches, according to Babak Ziaie, a professor of electrical and computer engineering and biomedical engineering at Purdue. "You need a relatively large force, a few pounds per square inch, to push medications through the microneedles and into the skin," he says. "It's very difficult to find a miniature pump that can provide that much force."

Seeking a solution, the Purdue researchers developed a simple, heat-activated pump that responds to human touch. Because it contains a liquid that boils at body temperature, the simple act of touching the pump with one’s finger induces vaporization of the liquid. This action, in turn, generates enough pressure to push the drugs through the microneedles and out to the desired target. From touch to delivery takes 20 to 30 seconds, the scientists state, and batteries are not required for use.

Stay tuned for my upcoming September editor’s column focused on microneedle-based drug-delivery technologies for more thoughts and information on this topic.