Effect of Magnesium Corrosion on Everolimus Release Kinetics for Bioabsorbable Nano Hybrid Coronary Stent

Magnesium alloy-based bioabsorbable cardiac stents have shown broad prospectives for the replacement of current scaffolds, but for complete use and replacement, it is necessary to determine the interaction between the magnesium alloy substrate and the drug loading system. The purpose of this study was to understand the effect of stents made of magnesium alloy on the speed and amount of drug release from it.

In this study, Everolimus was loaded on poly-L-lactic acid and coated as a nano-hybrid coating on a sample of magnesium alloy and cobalt-chromium alloy to investigate release in the simulated body fluid system. Also, the effect of pH and released hydrogen on drug release, corrosion and mass reduction of the sample with magnesium alloy base was measured and the efficiency of the drug-carrying polymer coating in reducing the corrosion rate of magnesium alloy sample was evaluated. For this purpose, UV / VIS spectrophotometer, hydrogen measurement system and scanning electron microscope were used.

The drug diffusion coefficient for magnesium base sample was calculated 6.06×10-10 and for sample with cobalt-chromium base was calculated 3.64×10-11 during the period of 50-100 days from the beginning of release, which was due to the production of hydrogen and corrosion products in magnesium stents. It was also found that the polylactic acid coating, is a good drug carrier and also it reduces the corrosion rate of magnesium stents. In addition, pH changes do not have much effect on drug release.

Magnesium stents have more drug release than conventional stents and are more capable to preventing re-stenosis.