Coating Techniques and Release Kinetics of Drug-Eluting Stents

Abstract

Implantation of drug-eluting stents (DESs) via percutaneous coronary intervention is the most popular treatment option to restore blood flow to occluded vasculature. The many devices currently used in clinic and under examination in research laboratories are manufactured using a variety of coating techniques to create the incorporated drug release platforms. These coating techniques offer various benefits including ease of use, expense of equipment, and design variability. This review paper discusses recent novel DES designs utilizing individual or a combination of these coating techniques and their resulting drug release profiles.

Keywords: Coronary stents; Drug release kinetics; Drug-eluting stents; Interventional cardiology; Stent coatings.

Fig. 1. Diagram of stent implantation.

The metal stent is fed via a catheter to the occlusion site and locally expanded (Reproduced with permission from Texas Heart Institute [6]. Copyright 2014 by Texas Heart Institute).

Fig. 2. Dip-coating schematic.

With a controlled speed, stent is submersed in the coating solution then removed and allowed for solvent evaporation, leaving the drug/polymer solution on the stent surface (Reproduced with permission from Schmidt and Menning [37]. Copyright 2000 by Sol Gel Gateway).

Fig. 3. EPD in solution schematic.

Drug and polymer particles are deposited onto the stent surface via an electrostatic attraction within the coating apparatus (Reproduced with permission from Ammam [46]. Copyright 2012 by Royal Society of Chemistry).

Fig. 4. Electrostatic dry powder deposition schematic.

Charged drug and polymer particles are deposited onto the stent surface via the apparatus shown above (Reproduced with permission from Nukala et al. [48]. Copyright 2009 by Springer Science+Business Media, LLC.).

Fig. 5. Spray coating system schematic.

Drug/polymer and solvent solution(s) is sprayed onto rotating stent to provide consistent coating along the stent’s luminal surface (Reproduced with permission from Shanshan et al. [60]. Copyright 2012 by Elsevier B.V. Publishing).