Preliminary experience with the V-flex plus coronary stent: immediate and one-month clinical outcome

Non-polymer drug-eluting coronary stents

Cardiovascular complications are leading causes of most fatalities. Coronary artery disease and surgical failures contribute to the death of the majority of patients. Advanced research in the field of medical devices like stents has efficiently resolved these problems. Clinically, drug-eluting stents have proven their efficacy and safety compared to bare metal stents, which have problems of in-stent restenosis. However, drug-loaded stents coated with polymers have shown adverse effects related to the stability and deterioration of the polymer coating over time. This results in late stent thrombosis and immunogenicity. These reasons laid the foundation for the development of non-polymeric drug-eluting stents. This review focuses on non-polymer drug-eluting stents loaded with different drugs like anti-inflammatory agents, anti-thrombotic, anti-platelet agents, immune suppressants and others. Surface modification techniques on stents like crystalline coating; microporous, macroporous, and nanoporous coatings; and chemically modified self-assembled monolayers are described in detail. There is also an update on clinically approved products and those under development.

Polymer-Free Drug-Eluting Stents: An Overview of Coating Strategies and Comparison with Polymer-Coated Drug-Eluting Stents

Clinical evaluations have proven the efficacy of drug-elution stents (DES) in reduction of in-stent restenosis rates as compared to drug-free bare metal stents (BMS). Typically, DES are metal stents that are covered with a polymer film loaded with anti-inflammatory or antiproliferative drugs that are released in a sustained manner. However, although favorable effects of the released drugs have been observed, the polymer coating as such has been associated with several adverse clinical effects, such as late stent thrombosis. Elimination of the polymeric carrier of DES may therefore potentially lead to safer DES. Several technologies have been developed to design polymer-free DES, such as the use of microporous stents and inorganic coatings that can be drug loaded. Several drugs, including sirolimus, tacrolimus, paclitaxel, and probucol have been used in the design of carrier-free stents. Due to the function of the polymeric coating to control the release kinetics of a drug, polymer-free stents are expected to have a faster drug elution rate, which may affect the therapeutic efficacy. However, several polymer-free stents have shown similar efficacy and safety as the first-generation DES, although the superiority of polymer-free DES has not been established in clinical trials.