MODELING POLYMERIC CONTROLLED DRUG RELEASE AND TRANSPORTPHENOMENA IN THE ARTERIAL TISSUE

We introduce and analyze a model for simulating the release of a drug from a polymeric matrix into the arterial tissue, with the aim to describe the phenomena that occur after the implantation of a cardiovascular drug eluting stent (DES). The main processes occurring in the polymeric matrix are drug dissolution and diffusion. Moreover, surface erosion, which consists in mass loss due to the degradation of the polymeric network, is considered as well. The drug eluted from the matrix is released in the arterial wall, modeled as a homogeneous porous medium. By consequence, we assume that drug molecules are transported by diffusion and convection. Moreover, inside the tissue the reversible reaction of the drug with specific binding sites is taken into account and the coupled problem of mass transfer between matrix and tissue is formulated. It is shown that the mass conservation principle leads to nonstandard boundary coupling conditions to describe the transfer of the drug between the matrix and the arterial wall. Then, the problem at hand is solved numerically, highlighting the importance of enforcing mass conservation and focusing on the influence of the polymer erosion on the drug release profile and drug distribution in the tissue.