Vascular stents are ‘spring-like’ cylindrical and hollow metal-based implantable devices for the treatment of vessel related blockages. It was supported by medical professionals to be a viable alternative to percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass graft (CABG) for the treatment of coronary atherosclerosis. Since the early 1990s, bare metal stents have started their implantation in patients throughout Asia. Cardiac surgeons have since then preferred the use of stents compared to balloon angioplasty as the rate of re-stenosis amongst patients have shown to decrease to about 20 to 25 percent as opposed to
PTCA’s 30 to 40 percent. Even though stents implantation is a costlier alternative to PTCA, the fact that it can prevent patients from a relapse and the need to receive a second interventional procedure warrants its increasing demand.
Though demand for bare metal stents has exceeded cheaper balloon angioplasty, the use of stents is not without problems. Being an implanted device, the human body tissue detects such devices as a foreign particle resulting in initial hyperplasia, a condition whereby endothelial cells grow to envelop the bare metal stents. This has been the main cause of re-stenosis amongst patients.
In order to counter this, researchers have come up with drug-coated stents. This coated drug acts as agent to inhibit tissue growth and thus prevent re-stenosis. These stents are referred to in the industry as drug-eluting stents (DES) as they have the capability to release drugs at a constant rate. The 2 most common drugs utilized in stents are Paclitaxel, which is licensed by Bristol-Myers, and
Squibb and Sirolimus, which is marketed by Wyeth Pharmaceuticals. Both of these drugs are suppressant drugs. Paclitaxel is used to treat tumor growth and Sirolimus prevents organ rejection.
In late 2005, the FDA