Everolimus Release Mechanism from Magnesium alloy Based Bioabsorbable Nanohybrid Coronary Stent

The impact of magnesium degradation on Everolimus release from WE43/PLLA nano-hybrid stent was compared with cobalt-chromium L605 alloy. Effect of Mg degradation on drug release from WE43/PLLA was much higher than from L605/PLLA. SEM, UV-VIS, FTIR, pH measurement, and H₂ evolution tests determined the hybrids’ property-change and drug release rate. Hydrogen evolution caused by magnesium degradation compelled Everolimus out without significant PLLA decomposition during the first 100 days, while formation caused PLLA shape change and cracking. A combined lattice/hole diffusion-dissolution mechanism governed the Everolimus release with the activation energies of 5.409 kJ/mol and 4.936 kJ/mol for the first 24 h and diffusion coefficients 6.06 x 10 -10 and 3.64 x 10 -11 cm2/s for the 50th to 100th days. The prolonged suppression of the hyperplasia within the smooth muscle cells by hybrid stent insertion could bring about restenosis cessation. As a result, implanting magnesium alloy stent in patients suffering from coronary artery problems and COVID19 can be more useful than current stents.