Comparison of pharmacokinetics of the sirolimus-eluting stent in Japanese patients with those in American patients

The aim of this study was to evaluate the pharmacokinetics of the sirolimus-eluting stent (SES) implanted in 20 Japanese patients with angina pectoris and compare it with that in US study. Bx VELOCITY stent loaded with a total sirolimus dose of 150 mu g was used in this study. Ten patients were treated by single-SES (group 1) and 10 patients were treated by double-SES (group 2). Sirolimus levels in whole blood were serially measured in the 2 groups after the SES implantation and compared with the pharmacokinetics in US study. We also evaluated the side effect of sirolimus, major adverse clinical events, and binary angiographic restenosis at 8 months after the SES implantation. Peak concentrations were observed approximately 4 hours after the SES implantation, and sirolimus half-lives were approximately 120 hours in each group. Mean peak sirolimus levels were 0.86 and 2.00 ng/mL for the group I and group 2, respectively. The peak concentrations of sirolimus in this study were twice higher in Japanese than in Americans, but they were much lower than effective concentration of sirolimus when orally administrated as an immunosuppressive agent. There were no side effects of sirolimus and no binary angiographic restenosis in any patients. One patient had target vessel revascularization at 8 months after the SES implantation. Although blood concentrations of sirolimus in Japanese patients after SES implantation are somewhat higher than those in American patients, its level is extremely low compared with the systemic administration, indicating the same clinical benefits by the SES could be safely expected in Japanese patients.