Development and Evaluation of Drug Eluting Stent Having Biphasic Release From a Single Layer of Biodegradable Polymer

In stent restenosis is the major disadvantage of percutaneous transluminal angioplasty. To overcome this limitation, drug eluting stents were introduced. We have developed novel sirolimus eluting stent using biocompatible and biodegradable polymer matrix. Developed stent have biphasic release profile for sirolimus from a single layer of polymer matrix, having blend of slow and fast degrading polymers. Coating integrity of coated stents were evaluated after crimping and postexpansion with the help of scanning electron microscopy while thickness of coated stent was measured using destructive test method. This shows that drug-polymers bilayer was uniformly coated with the average thickness of 5.2 μms. There was no deformation after crimping and expansion of the stent. We have also measured in vitro and in vivo release profiles of sirolimus from stents which shows biphasic release characteristics, i.e., initial burst period followed by sustained release. In vitro release profile is well correlated with in vivo release in blood and arterial tissues. Developed stents showed good efficacy and safety in porcine coronary artery model.