Figure 7.

Different types of stent-based drug delivery systems: (A) drug released by diffusion from the polymer, (B) drug released by diffusion through a rate-limiting coating, (C) drug released by swelling of the layer, (D) drug release directly from the surface, (E) drug loaded in pore or reservoir in-stent, (F) drug release by the erosion of the polymer coating, (G) drug loaded in a nanoporous reservoir in a sheet, (H) drug packed between coating layers, (I) drug released by hydrolysis or enzymatic action from a polymer, and (J) bioerodable polymer-coating stent.