Two Core Application Directions of Drug Coatings

Drug coatings play a central role in vascular interventional therapy. Their two major application carriers — Drug-Eluting Stents (DES) and Drug-Coated Balloons (DCB) — provide complementary solutions for the treatment of vascular restenosis through distinct design logics and modes of action. This article analyzes their core functions, structural principles, and clinical application differences in detail, clarifying their value in interventional therapy.

Drug-Coated Balloons (DCB) and Drug-Eluting Stents (DES) are two key devices for inhibiting vascular restenosis in interventional therapy. Both exert effects through local drug release, but differ significantly in design principles, mechanisms of action, and clinical indications, forming a complementary therapeutic strategy.

1 Drug-Coated Balloon (DCB)

A drug-coated balloon is an interventional medical device used to treat arterial stenosis or occlusive diseases (such as coronary artery disease and peripheral arterial disease). Its core function is to achieve vascular recanalization and restenosis prevention through the dual effects of mechanical dilatation + local drug delivery, with no foreign body residue after the procedure.

Core Functions

• Mechanical vascular dilatation: Using physical pressure from balloon expansion to open stenotic or occluded vessels and quickly restore blood flow.

• Local drug release: The balloon surface is coated with antiproliferative drugs (e.g., paclitaxel), which are rapidly released into the vessel wall during dilatation to inhibit excessive intimal hyperplasia and reduce the risk of restenosis.

• No foreign body retention: Unlike DES, DCB does not require permanent implantation of a metallic stent in the vessel, reducing long-term foreign body reactions and thrombosis risks.

Structure and Working Principle

• Structure: Mainly consists of an expandable balloon catheter (for mechanical dilatation), a drug coating (drug plus hydrophilic matrix to ensure rapid and uniform release), and a delivery system (for precise positioning to the lesion).

• Mechanism: During balloon expansion, the vessel wall is compressed, opening the stenotic segment while the drug coating comes into close contact with the vessel wall. The drug rapidly penetrates the vascular endothelium and media within 30–60 seconds. By blocking cell division (e.g., paclitaxel inhibits microtubule polymerization), it reduces smooth muscle cell proliferation and inflammatory responses, thereby preventing restenosis.

The core value of DCB lies in reducing vascular intimal hyperplasia and avoiding foreign body retention, making it especially suitable for small-vessel lesions, in-stent restenosis, and patients at high bleeding risk. Recently, new products such as rapamycin-coated balloons have achieved rapid research and development breakthroughs, further broadening their clinical application prospects.

2 Drug-Eluting Stent (DES)

A drug-eluting stent consists of a metallic stent platform, a polymeric coating, and an antiproliferative drug. It combines mechanical support with long-term sustained drug release, and is mainly used to open stenotic or occluded vessels and prevent post-procedural restenosis, representing a classic solution for coronary interventional therapy.

Core Functions

• Mechanical vascular support: Similar to Bare Metal Stents (BMS), it mechanically dilates stenotic vessels, restores blood flow, and relieves angina or myocardial ischemia.

• Prevention of post-procedural restenosis: After vascular injury, excessive proliferation and migration of smooth muscle cells lead to intimal hyperplasia and recurrent vessel occlusion. Antiproliferative drugs on the stent surface inhibit cell division and reduce scar tissue formation, lowering the restenosis rate from 20–30% (bare stents) to 5–10%.

• Reduced thrombosis risk: The polymer carrier controls drug release kinetics, balancing antiproliferative effects with endothelial healing and lowering acute/subacute thrombosis risk.

• Improved long-term prognosis: Reduces the need for repeat interventions (e.g., re-stenting or bypass surgery) and enhances patients’ quality of life.

Structure and Drug Release Mechanism

• Structure: Metallic stent base (usually cobalt-chromium or platinum-chromium alloy for mechanical support), drug coating (antiproliferative agents such as rapamycin derivatives or paclitaxel), and polymer carrier (biocompatible materials such as PLGA for controlled sustained release).

• Release mechanism: The polymer carrier gradually degrades, releasing the drug slowly over weeks to months. The drug acts locally on vascular tissue around the stent to inhibit smooth muscle cell proliferation while minimizing systemic side effects.

3 Comparison of Core Functions Between the Two Technologies

In summary, as the two core application directions of drug coatings, drug-coated balloons and drug-eluting stents adapt to different clinical scenarios with their respective strengths of no foreign body retention and long-term mechanical support. Their combined application has greatly expanded the options in vascular interventional therapy, providing important support for improving therapeutic outcomes and patient prognosis.