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Antimicrobial-Infused Polymer Demonstrates Backbone
Implants often rely on antimicrobial coatings to prevent infections. But the release of antibacterial agents via diffusion from a biomaterial’s surface may not be the most effective approach for combating biofilm formation on implants. With this in mind,

Bob Michaels

Implants often rely on antimicrobial coatings to prevent infections. But the release of antibacterial agents via diffusion from a biomaterial’s surface may not be the most effective approach for combating biofilm formation on implants. With this in mind, Interface Biologics (Toronto; www.interfacebiologics.com) is developing a technology platform that it claims will prevent biofilm formation more effectively than coatings, last longer in the body, and kill a broader spectrum of microbes.

In development since 2002, the company’s Epidel platform differs from traditional antimicrobial technologies in that it is not applied to the surface of a device. “What makes it unique is that the antibiotic is actually not admixed into the polymer matrix, but is an integral part of the polymer,” explains Frank LaRonde, senior scientist at Interface Biologics and Epidel team leader. “It’s part of the backbone of the polymer. What that gives you is a polymer that is able to degrade over a longer period of time, providing the pharmaceutical that you have incorporated into that backbone.”

Surface coatings tend to release antibiotics too rapidly, failing to reduce the frequency of infection, according to the company. In contrast, Epidel’s polymer chemistry degrades in the body in the presence of enzymes that are generated by inflammatory white blood cells. Once healing occurs, the level of enzyme production decreases, slowing the release of the antibiotic. The release of the drug occurs from within the polymer to counter the formation of biofilm and the incidence of infection.

Longevity also sets Epidel apart from silver-based antimicrobial coatings, notes Tom Reeves, Interface Biologics’s president and CEO. Tests have shown that after 90 days, 90% of the polymer and 90% of the drug are still present. Silver-based coatings, on the other hand, tend to last in the body approximately 15 days maximum, according to LaRonde. “We’ve done benchmark studies with a number of silver-based products and our products. And in the experiments we ran, the silver gave up after one to three days.”

“There are a lot of people that have silver-based [coating] technologies,” Reeves adds. “Those are primarily for coating a catheter, a lead, or something like that. The makeup of this product is such that it’s unique in terms of the release profile and the ability to kill a broad range of bugs with a much lower concentration of antibiotics than you would normally have to use.”

The technology also has the unique ability to be spun into fibers. “Because the material is a polyurethane, we can make it any molecular weight of that polymer that we want,” LaRonde says. “We can make polymers that have the ability to be spun into fibers, giving rise to a number of different applicable areas, such as sutures.” As a spun fiber, the material can potentially also be used to manufacture dialysis cuffs, wound dressings, hernia mesh, and other medical devices.

Still in development, the technology platform for use with a urinary catheter could hit the market in 2011, according to the company. “The time frame for the fiber applications of Epidel won’t be too far beyond that,” Reeves says.

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