Drug-Eluting Polymer Developed at UA is Revolutionizing Coronary Surgery

Akron, Ohio March 16, 2005 - Researchers at The University of Akron have developed and patented a new polymer that has led to radically less-invasive surgery for coronary care. The new materials are integral components of coronary procedures that have dramatically improved alternatives to the half million coronary bypass operations performed each year in the U.S.

The new polymer is being used to coat stents that are inserted in the area of an arterial blockage. The polymer coatings were designed so that manufacturers could infuse them with drugs that are released internally for a long period of time.

The new, medicated stents offer such substantial benefits over traditional procedures that the number of coronary bypass operations have plummeted as much as 85 percent.

Stents are mesh tubes used to prop open a blocked artery. The stent is collapsed to a small diameter and placed over a balloon catheter which is moved through the arteries into the area of the blockage. When the balloon is inflated, the stent expands and forms a permanent scaffold. The stent stays in the artery and holds it open. It improves blood flow to the heart muscle and relieves symptoms.

Stents made of naked metal are of limited use because of the body's tendency to re-close arteries beyond the stent. This process, called restenosis (pronounced: ree-STEN-o-sis), occurs in nearly one-third of patients who receive stents made of uncoated metal.

Dr. Joseph Kennedy, a distinguished professor of polymer science and a distinguished professor of chemistry at The University of Akron, developed the polymeric material used to coat stents. The novel thermoplastic elastomer expands over the mesh tube, and is infused with the drug Paclitaxel. The drug is released over a long period of time, and prevents restenosis.

The University of Akron technology was licensed by a large bio-device manufacturer, and received FDA approval in March, 2004, and is being used for commercial applications. The fundamentally new biomaterial, conceived and produced in the laboratory only fifteen years ago, has shown superior biocompatibility and biostability.

Clinical studies have shown stents coated with Kennedy's drug-containing polymer practically eliminates restenosis.

There are more than a half million coronary bypass operations in the United States each year, Kennedy says. That invasive surgery can take four to five hours to complete, and requires harvesting a blood vessel from another part of the body.

Using coronary stents, the surgeon can accomplish similar results in a much simpler procedure that lasts less than an hour, and requires a relatively minor incision, he said.

In addition to the half million bypass operations, more than 800,000 men and 400,000 women have angioplasties each year in the United States. Drug-eluting stents can make those procedures safer, and more permanent.

Our polymers satisfy the many requirements of such a demanding application as coronary stents, including biocompatibility and hemocompatibility, controlled drug release, sterilization, confluent stent coating, and intrinsic mechanical properties of the coating layer that withstand the stresses incurred during stent insertion and expansion without compromising the integrity of the coating.

These polymers also promise to be useful in other biomedical applications as well that require biostability, Dr. Kennedy says.

Dr. Judit E. Puskas, one of the co-inventors of the polymer being used on stents, and inventor of other biomaterials, recently joined The University of Akron as the Lanxess Professor of Polymer Science. She now is working with Kennedy to continue research into other uses for the existing polymer and to develop additional new polymers for biomedical applications.