Biomedical Engineering Reference
In-Depth Information
On the Role of Phase Change in Modelling
Drug-Eluting Stents
Franz Bozsak, Jean-Marc Chomaz, Abdul I. Barakat
and Giuseppe Pontrelli
Abstract
A model of drug release from an eluting stent to the arterial wall is
presented. The coating layer is described as a porous reservoir where the drug is
initially loaded in a polymer-encapsulated solid phase, and is then released both to
the coating and to the tissue of the arterial wall in a free phase. The wall is treated
as a heterogeneous porous medium and the drug transfer through it is modeled
by a non-homogeneous set of coupled partial differential equations that describe
a convection-diffusion-reaction process. Change of phases due to drug dissolution
in the coating and binding-unbinding reactions in the arterial wall are addressed.
Numerical results show a strong coupling of the release kinetics in the polymer and
the drug dynamics in the wall, and this coupling depends on the physico-chemical
drug properties, the microstructure of the polymeric stent coating and the properties
of the arterial wall.
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Keywords
Drug delivery
Drug-eluting stents
Local mass non-equilibrium
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Two-phase mass transfer
Diffusion-convection-reaction equations
1 Introduction
Drug-eluting stents (DES) have drastically reduced the rate of restenosis compared to
bare-metal stents and have since become the most common choice for the treatment
of coronary arteries afflicted with advanced atherosclerotic lesions. DES consist
of a metallic wire mesh platform coated with a polymer film that encapsulates a
therapeutic drug aimed at preventing hyperplasia of smooth muscle cells (SMCs)
responsible for the re-occulsion of the treated artery, termed restenosis. To ensure
effective performance, both the stent geometry and the coating design need to be
optimized. The success of an antiproliferative drug therapy from a DES depends on
