Numerical Modeling of the Effects of Magnetic Field on Drug Transport for the Optimization of Drug-Eluting Stents
Date
2024-05-08
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Abstract
This in-silico study investigates the impact of Magnetic Field (MF) on drug release from Drug-Eluting Stents (DESs) and its transport through the coronary arterial wall. Utilizing continuum modeling of mass balance, governing equations for both the polymer and media layers were developed based on porous media theory. These equations were then nondimensionalized, discretized, and then solved numerically using the Finite Volume Method (FVM). The findings reveal a significant increase in the concentration of drug particles near the stent strut. This increased concentration of free drug enhances its availability for both types of drug receptors, facilitating absorption and distribution over a wider area. Additionally, the positive influence of the MF on the velocity field extends beyond the tissue, leading to a delay in drug depletion on the polymer side. The counterintuitive simultaneous increase in dissolved drug in both the polymer and media layers was observed, attributed to drug mass fluxes through the polymer topcoat layer and the top layer of the media, where the drug exits the computational domain. Furthermore, both the rates of media layer filling and depletion decrease for a while in the presence of the MF, which is advantageous. However, a short period resembling conditions without the MF occurs after the decrease. Interestingly, mass flux rates higher than those without the MF result in a reversal of this trend. Experiencing this undesirable increase in drug depletion does not negate the favorable effect of the MF, as drug accumulation in the tissue has already begun during the initial stages of drug release. The maximum averaged concentrations of free drug in the tissue and dissolved drug in the polymer increase nonlinearly with MF strength, with a more pronounced effect observed in the polymer. Moreover, the time at which the tissue reaches its maximum drug content occurs earlier with increasing MF strength, while the dissolved phase experiences a delayed peak. The effect of the MF on drug particle transport was further characterized by determining the center of mass, revealing a non-monotonic variation over time comprising two linear stages. Increasing MF strength is associated with a stronger tendency for the center of mass to be closer to the top surface of the polymer. Overall, this study demonstrates that the presence of an MF can enhance the efficiency of polymer drug release kinetics, potentially aiding in the development of DESs with smaller strut and thinner coating layer, thus reducing stent failure. Moreover, the study identifies values for equivalent polymer thickness and width corresponding to different MF intensities.
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Keywords
Convection-Diffusion-Reaction, Porous Media, Numerical Simulation, Non-uniform Magnetic Field, Implant Assisted-magnetic Drug Targeting, Stent Size Optimization, Tissue Permeability, Blood Viscosity
Citation
Vahedi, S. M. (2024). Numerical modeling of the effects of magnetic field on drug transport for the optimization of drug-eluting stents (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.