HOW THE SIROLIMOUS-RELEASING DYNAMICS CHANGE WHEN ADVENTITIA LAYER AND DRUG METABOLISM ARE TAKEN INTO ACCOUNT

Nowadays, the drug-eluting stent application has boomed as an effective treatment for coronary anery blockage. Experimental determination of the spatio-temporalvariation of drug concentration in the arterial wall as well as the polymeric coating is very expensive and even impossible for many cases. In this paper, the volunte-averaged porous media equations were developed to solve for transport through the porous arterial layers. The established equations are solved numerically by using thefinite-volume method. The elfects of adding adventilia layer and the drug consumption at the surface of Vasa vasonun cells in the mathematical modeling were considered as two important factors on drug phannacokinetics. These models have been presented in two types of interface conditions, real porosity, and equal porosity, for the coating-media and media-advemitia interfaces, respectively. It was assumed that the injuries due to the angioplasty procedure penetrate to the depth of the media layer to have a more realistic simulation. The results showed that drug-containing polymer is diffusion- dominated and the porosity difference of the layers is the most effective factor for drug release dynamics in comparison to adding the adventitia layer and considering the sink condition there. Neglecting the adventitia layer causes a faster drug depletion during release action. While considering the drug reaction and washing out via Vasa vasonnn cells have an inverse effect. The results show that although these two factors have a significant impact on the arterial drug uptake, the polymer does not change due to its low porosity. Utilizing the real porosities results in a considerable increase in concentration level. Therefore, dome shape of temporal variation of the normalized drug.‘ concentration profile in the media layer becomes more tapered when the difference of porosities not taken into account. Altogether. the results imply on the noticeable effect of interface condition on drug dynamics.

Keywords:

Drug-Eluting Stents (DES) , Porous media , Convection-diffilsion-reaction equation , Atherosclerosis , Phamiaeokinetics