Fighting Heart Disease with Drug-releasing Stents

The Problem

Cardiovascular stents, which open clogged, damaged or narrowed arteries due to coronary artery disease, have saved millions of lives since the first FDA approval of the devices in 1994. However, once implanted these stents can cause the body to clot and re-clog the artery or cause restenosis, where there is a narrowing of the artery again after implantation. As recently as 2007, up to 50 percent of all stent patients suffered from restenosis.

Medical device companies were looking for innovative ways to combat these side effects. Dr. Leonard Pinchuk, a biomaterials scientist with Boston Scientific, believed there was a way to do so using the stents themselves, but he needed to find the correct material.

The Expert

Dr. Joseph Kennedy, a distinguished professor of polymer science and chemistry in the Department of Polymer Science at the University of Akron, had long studied and developed biostable elastomers in various capacities, but not for medical devices.

Several companies and individuals referred Boston Scientific’s Pinchuk to Kennedy as someone who could create the material he needed. In fact, thanks to Kennedy’s work, the University of Akron already had intellectual property through his creation of a polystyrene-polyisobutylene-polystyrene block copolymer, known as SIBS.

The Solution

The two scientists began working together and found that this biostable thermoplastic elastomer, which acts much like silicone rubber and polyurethane, could be an ideal coating for medical stents.

This SIBS material became the basis for a stent that could hold pharmaceutical products within its coating. The layer was designed with controlled permeation characteristics to enable the time-release delivery of those drugs.

In particular, Boston Scientific’s TAXUS® drug-eluting cardiovascular stent received FDA approval for use in 2004. The TAXUS stent, coated with this SIBS biomaterial, holds the drug Paclitaxel, which is distributed into the bloodstream over time to prevent restenosis, a common side effect of stent treatment of arteries.

TAXUS was the second drug-eluting stent of its kind and was a massive medical device launch at the time. TAXUS has since been implanted in millions of patients worldwide, and by 2011 was the best-selling stent on the market, with more than $1.5 billion in sales. Today, the worldwide stent market is estimated to be $6.4 billion, with more than one million stents implanted annually in the U.S. Thanks in large part to its TAXUS stent, Boston Scientific is one of the leading medical device companies in the world, generating some 32 percent of its annual revenue through its cardiovascular business.