Originally Published MDDI November 2004

R&D DIGEST

Thin Film Could Become Drug-Delivery Device

Brendan Gill

Researchers have developed a microthin film that, in the future, may allow patients to take medication through heat-controlled drug implants.

The group, led by Andrew Lyon, associate professor at the Georgia Institute of Technology (Atlanta), tested insulin release using microthin films during an 18-month period. The group used a multilayering procedure to assemble the films from microparticles, which allowed for greater control over drug release than using bulk material.

“This is another great example of how layer-by-layer polymers can be used to create film structures and properties not easily realized by other techniques,” says Michael Rubner, professor of polymer materials science and engineering at the Massachusetts Institute of Technology (Cambridge, MA).

The films were loaded with insulin that released after they were heated to 31°C, six degrees below human body temperature. The release was stable, and the films continued to emit insulin for more than a month.

Although the results were encouraging, Lyon and his team are working to increase the release point to above human body temperature. That would help prevent overdoses, which could occur if body temperature rises too high.

“It could be catastrophic if [a patient with an implant] ran a marathon or ran a fever,” Lyon says. “We don't want the release to be affected by changes in body temperature.”

Accidental overdoses are not the only risks associated with implantable drug-delivery systems. Inflammation, the rejection of the implant, and the formation of scar tissue around the implant itself can decrease the efficacy of the drug delivery, Lyon says. There is also the issue of going under the knife every time an implant needs to be refilled. “Who would want to undergo periodic microsurgeries to fill their prescription?” asks Lyon.

The next step for Lyon and his team is to find a way to get a bigger pulse out of the film and more tightly regulate when the film is activated. These issues must be resolved before heat-controlled drug implants can have any practical use.

“The near-term impact [of this research] on the population is minimal,” Lyon says.

Ronald Siegel, head of pharmaceutics at the University of Minnesota, also cautions against building up Lyon's discoveries. The findings are encouraging, he says, but they don't mean that diabetics or patients undergoing hormone therapy will receive their dosages with implantable drugs anytime soon.

“We don't want to jump to the conclusion that a product will be coming out in a few years,” he says. “This is very nice work. It's just not ready for prime time.”

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