Drug release kinetics from a drug-eluting stent with asymmetrical coat.

The aim of this study was to investigate the drug release profiles of biodegradable polymer sirolimus- or paclitaxel-eluting stents with asymmetrical coating (BPSES-A or BPPES-A) both in vitro and in vivo. In vitro, the drug release profile was characterized by measuring the drug concentration by HPLC over a time-course. In vivo, a porcine aorta stenting model was employed. The results showed that the drug release rates of BPSES-A and BPPES-A were slower, more stable and less burst releasing than those of conventionally coated stents (BPSES-C and BPPES-C respectively), both in vitro and in vivo. Based on the in vivo results, the sirolimus and paclitaxel content of the local coronary wall was maintained at a higher and more effective level with BPSES-A and BPPES-A than with BPSES-C and BPPES-C, respectively. The drug levels in peripheral tissue samples were below detection levels. These data demonstrated the effectiveness of both sirolimus and paclitaxel as stent coating agents, and revealed the favorable drug release kinetics and pharmacokinetics of asymmetrical coated stents compared with conventional coated stents.