Two-phase transport of drug in stent-based drug delivery

Abstract

The present work enlightens the two-phase transport mechanism of drug within the vessel wall from a half-embedded drug-eluting stent, having struts with circular cross-section. The arterial wall is idealized as a single homogeneous layer with identical diffusivity property. The plasma filtration through the blood-tissue interface is allowed only in transmural direction. The governing equation of interstitial fluid (ISF) flow within the vessel wall is modelled by the Brinkman equation and the equation of continuity. When the drug is distributed within the arterial wall, there is also occurrence of binding of the drug binding of the drug to receptors present on the cell surface. So, the study incorporates both free-phase and bound-phase drug transport. The free drug transport is modelled by using a convection-diffusion-reaction process, whereas, the distribution of bound drug is modelled by an unsteady reaction process only. All the governing equations along with suitable boundary and initial conditions are formulated by using a two-dimensional cylindrical polar coordinate system and successfully solved numerically by using the Marker-and-Cell (MAC) method in a staggered system. The study highlights the influence of several clinical parameters in drug delivery and their optimality, which may enhance the safety and efficacy of the device.