Polymers for Drug Eluting Stents

Currently approved drug eluting stents (DES) consist of a metallic scaffold and an elutable drug dispersed in a polymer matrix that conformally surrounds the struts. These primarily biostable polymers bind the drug to the stent and modulate the elution of the drug into the arterial tissue. This chapter summarizes the key requirements for polymers used in the DES, including physical properties, stability, compatibility with drugs, biocompatibility with vascular tissue and control of drug release. An in-depth analysis of polymer structure, coating design, drug-polymer morphology and drug elution profile is provided for the four currently marketed DES: CYPHER(R) Sirolimus-eluting Coronary Stent, Taxus(R) / Taxus Liberte(R), XIENCE V (TM) / Promus(R) and Endeavor(R). A new generation of DES is being developed using bioabsorbable polymers which degrade over time and leave behind a bare metal stent. This includes the RES TECHNOLOGY (TM) platform employed in the NEVO (TM) Sirolimus-eluting Coronary Stent which is explored with respect to polymer composition, degradation profile and drug release kinetics.