Paclitaxel drug-eluting stents : The science behind the success

Drug-eluting stents (DES) utilize complex systems to ensure controlled, localized delivery of therapeutic agents to the target site. The success and clinical utility of a DES is driven by the judicious selection of the drug and the polymer carrier. These two components of DES are discussed in this review article that focuses on the TAXUS Express 2™ Paclitaxel-Eluting Coronary Stent System (Boston Scientific, Natick, Massachusetts). The clinical trial program of the TAXUS Express system comprises the largest dataset of randomized clinical trials and registries of DES systems, demonstrating robust clinical benefits in the prevention of restenosis across a broad range of patient and lesion types. The TAXUS Express system elutes paclitaxel, which potently inhibits crucial events in the restenotic cascade. Paclitaxel is eluted from poly(styrene-b-isobutylene-b-styrene) (SIBS), an elastomeric vascular-compatible polymer carrier. Paclitaxel has demonstrated effective inhibition of proliferation and migration of smooth muscle cells in bench, preclinical and clinical studies, proving its merit as an antirestenotic agent. The physicochemical, mechanical and biological properties of the SIBS polymer provide controlled release of paclitaxel and excellent biocompatibility in animal models of restenosis, indicative of the short- and long-term safety features necessary for a DES polymer. Future developments are also discussed, including structural alterations in stents, such as those used in the second-generation TAXUS stent (the TAXUS® Liberte™ stent [Boston Scientific]), as well as the use of biodegradable stents and polymers.