In vivo and in vitro characterization of poly(styrene-b-isobutylene-b-styrene) copolymer stent coatings for biostability, vascular compatibility and mechanical integrity.
The TAXUS Express 2 Paclitaxel Eluting Coronary Stent System employs a coating consisting of the thermoplastic elastomer, poly(styrene-b-isobutylene-b-styrene; SIBS), selected for its drug-eluting characteristics, vascular compatibility, mechanical properties, and biostability. This study was conducted to evaluate the impact of different SIBS (17-51 mole % styrene) compositions on mechanical properties, chemical stability, and vascular compatibility. Mechanical property (stress-strain measurements) and stability studies were conducted on polymer films with five different styrene contents (17, 24, 32, 39, and 51 mole %). The ultimate tensile strength did not change significantly with composition, but the elongation at break decreased with increased styrene content. A pulsatile fatigue test further confirmed the mechanical stability of SIBS up to 39 mole % styrene. The vascular compatibility of five different SIBS compositions was assessed using SIBS-only coated stents, in the coronary and carotid arteries in a porcine model study. The stability of the vessel wall, rate/degree of endothelialization, inflammation, and thrombus at timepoints from 30 to 180 days were evaluated. The results confirm vascular compatibility over the range of 17-51 mole % styrene.
Strickler
Fred
F
Boston Scientific Corporation, One Boston Scientific Place, Natick, Massachusetts 01760, USA.
Richard
Robert
R
McFadden
Sharon
S
Lindquist
Jeff
J
Schwarz
Marlene C
MC
Faust
Rudolf
R
Wilson
Gregory J
GJ
Boden
Mark
M
D000792:Angiography; D000818:Animals; D001672:Biocompatible Materials; D002339:Carotid Arteries / Q000033:anatomy & histology; D003326:Coronary Circulation / Q000502:physiology; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D015607:Stents; D013314:Stress, Mechanical; D013343:Styrenes / Q000737:chemistry*; D013552:Swine; D013718:Tensile Strength
D001672:Biocompatible Materials; D013343:Styrenes; C500040:poly(styrene-b-isobutylene-b-styrene)