What Is In-Stent Restenosis?

A drug-eluting stent (DES) is a stent that uses a bare metal stent platform to carry (load) anti-vascular intimal hyperplasia. The effective application of drug-eluting stents can greatly reduce the incidence of restenosis and re-interventional surgery, but it has not reduced the mortality rate. There were no significant differences in the incidence of clinical endpoint events between different drug-eluting stents, and some secondary endpoints benefited. Drug-eluting stents include bare stents made of stainless steel or cobalt-chromium. These stents are covered by antiproliferative drug carriers. Their polymer drug-containing coatings include permanent, degradable and polymer-free drug-containing coatings. Layer technology, which includes drugs such as limolimus and paclitaxel.

Basic Information

Chinese name

Drug eluting stent

Foreign name

DES

Drugs on board

Ballimos, Navomos and Malimos, etc.

Drug-eluting stent polymer drug-loaded coating technology

1. Permanent polymer drug-loaded coating technology The permanent polymer drug-loaded coating technology is the basic technology of drug-eluting stents for drug loading. The key is the polymer drug-loaded coating technology. The inner coating can increase the adhesion with the stent The drug-loaded coating contains the drug, and the outer coating controls the rate of drug release. Drug-eluting stents have high requirements for permanent polymers, require good biocompatibility, and have no or only minimal inflammatory effects. Some drug-eluting stents use the outer surface of the stent or asymmetric polymer drug-loaded coating technology to reduce the effect of inflammatory effects on stent repair and coverage. The drug in the permanent polymer drug-loaded coating is released by dissolving the microparticles, and then enters the blood vessel wall by passive diffusion. Drug loading can also be stored as a solution in a polymer film or directly dissolved in a polymer matrix. Drug release can be controlled by dispersion, chemical reactions, and solvent activation.
2. Degradable polymer drug-loaded coating technology Animal and clinical studies have shown that permanent polymer drug-loaded coating technology is likely to be a source of stimulus to hypersensitivity and inflammatory response, which is related to late clinical (1-12 months) ) And late-late (> 1 year) intrastent thrombosis and delayed restenosis. Degradable polymer drug-loaded coatings are theoretically the same as bare metal stents after degradation and can improve the late-stage safety of drug-eluting stents. However, the degradable polymer drug-loaded coating technology itself is very challenging. It is necessary to clarify its ideal biocompatibility, composition, composition and degradation time, and pay special attention to the pharmacokinetics of the antiproliferative drug after the coating is released , And variation in coating degradation time. The degradable polymer drug-loaded coating releases the drug through a dual pathway of drug dispersion and polymer degradation. Polymers also have an inflammatory effect when they are degraded, and sometimes produce an acidic environment, which can also cause complications due to the body's immune response to degraded monomers. These uncertain aspects should be studied, with a focus on long-term clinical follow-up results.
3. Polymer-free drug-loaded coating technology (1) In order to completely eliminate the potential risk of increasing the sensitization and inflammation of polymer drug-loaded coatings in drug-eluting stents to late and late thrombosis, polymer-free drug-loaded coatings Layer technology is imperative and has made a breakthrough. Its advantage is that it can avoid the adverse reactions of the polymer drug-loaded coating, and theoretically does not affect the repair, healing and coverage of the inner membrane of the stent. It can also eliminate the cracking, peeling and accumulation of the polymer drug-loaded coating, thereby maintaining the Integrity.
(2) Polymer-free drug-loaded coating technology includes: pure drug is poured into micro-blind holes or nano-pores on the surface of the stent wire; the drug is dissolved in the bioabsorbable carrier on the surface of the stent with a non-polymer drug-loaded coating; The active substances are bound by covalent bonds or attached to the surface of the scaffold in the form of crystals or chemical precipitation.

Drugs in drug-eluting stents

The purpose of drug-eluting stents is to inhibit the intimal hyperplasia of the stent and prevent the restenosis of the stent. The drug used should have the following characteristics: a wide treatment window, low risk of inflammation, selective inhibition of smooth muscle cell proliferation without toxicity to the medial and adventitia of blood vessels, and does not affect the repair and endothelialization of the stent. Its efficacy depends not only on the biological activity in vitro, but also on the local pharmacokinetics and physicochemical properties of the drug; the distribution of the drug in the vascular wall tissue is mediated by the stent and driven by the balance of the dispersive force. Water-soluble drugs such as heparin easily penetrate into tissues, but they also clear quickly. Conversely, fat-soluble drugs such as paclitaxel or limolimus are insoluble in water and can only bind to hydrophobic spots in the arterial wall. Although both water-soluble and fat-soluble drugs have a large spatial concentration gradient in the arterial wall, the distribution of fat-soluble drugs is more uniform than that of water-soluble drugs. Only the immunosuppressant limox family and the anti-proliferative drug paclitaxel are used in drug-eluting stents. The former includes sirolimus, everolimus, sotalumox, balimoxid, and navomox. Division and Malimos.