New Drug-Eluting Stents

Drug-eluting stents (DES)were primarily conceived to reduce in-stent neointimal formation and therefore minimize the occurrence of restenosis, the major drawback of percutaneous coronary interventions with bare-metal stents (BMS).The development of DES has been pioneered through a combination of the increased understanding of the biology of restenosis, the selection of drugs that target 1 or more pathways in the restenotic process, controlled-release drug delivery strategies, and the use of the stent as a delivery platform.Although first-generation DES Cypher (sirolimus-eluting stent; Cordis Corporation, Johnson & Johnson, Warren, NJ) and Taxus (paclitaxel-eluting stent; Boston Scientific Corporation, Natick, Mass) have effectively achieved their main goal, reducing restenosis across virtually all lesion and patient subsets, their safety has been limited by suboptimal polymer biocompatibility, delayed stent endothelialization leading to late and very late thrombosis, and local drug toxicity.1,–,9Both Cypher and Taxus use durable thick polymers to carry and control the release of their antiproliferative agents. The permanent presence of these polymers has been correlated to inflammatory responses and local toxicity in preclinical analysis.10,–,13 Furthermore, durable polymers used in first-generation DES have been associated with mechanical complications (eg, polymer delamination and “webbed” polymer surface leading to stent expansion issues)14 and nonuniform coating resulting in erratic drug distribution. As a consequence, in recent years, the focus of clinical research has been on the development of novel drug carrier systems including absorbable (or biodegradable) polymers and nonpolymeric stent surfaces. Additional improvements include the development of more modern platforms (eg, better deliverability, radiopacity, flexibility, and radial strength) as well as the use of novel antiproliferative agents or reduced doses of current approved antiproliferative drugs.This review focuses on describing next-generation drug-eluting stent systems based on the use of novel coatings and carrier systems developed to …