Polymer-Free Drug Coating for Endovascular Stent Profile Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current stents face challenges with restenosis due to inflammation and thrombosis, which lead to smooth muscle cell proliferation and vessel closure, and existing drug-eluting stents have limitations in reducing stent profile, causing irritation and inflammation, and controlling drug release rates.
Innovation Solution
A radially expandable stent with a metallic filament body and a liquid-infusible mechanical anchoring layer, coated with a substantially polymer-free composition of an anti-restenosis drug, allowing direct contact with the vessel wall and controlled drug release through a continuous surface stratum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If polymer-based drug delivery coatings are used on stents, then drug release is achieved, but stent profile is increased and irritation/inflammation is caused
Solution Approach 1:
The patent extracts and removes the polymer carrier material from the drug delivery system, leaving only the active drug substance deposited directly on the stent surface. This eliminates the polymer-related irritation and inflammation while maintaining drug delivery capability through direct drug contact with tissue
Solution Approach 2:
The patent uses a small molecule carrier or direct deposition method as an intermediary between the drug and tissue, replacing the problematic polymer matrix. This intermediary enables controlled drug release without the harmful effects of polymer degradation and foreign body response
2Quantity of substance
If polymer coatings are used for drug delivery, then drug release is enabled, but stent profile is increased
Solution Approach 1:
The polymer carrier is extracted and removed from the system, allowing the drug to be deposited in a thin layer directly on the stent surface. This dramatically reduces the coating thickness and overall stent profile while preserving the drug delivery function
Solution Approach 2:
The patent employs thin film deposition techniques to apply the drug coating in a ultra-thin layer without requiring bulky polymer matrices. This achieves effective drug delivery with minimal increase in stent profile
3Quantity of substance
If polymer-based drug delivery systems are used, then drug release is achieved, but control over drug release rate is limited
Solution Approach 1:
The patent controls drug release rate by changing physical parameters such as drug crystallinity, particle size, coating thickness, and deposition density rather than relying on polymer degradation kinetics. This provides more precise and tunable control over release rates
4Strength
If stents are used to provide mechanical support, then vessel collapse is prevented, but restenosis occurs due to inflammation and thrombosis
Solution Approach 1:
The patent applies anti-proliferative drugs directly to the stent surface before implantation to preemptively inhibit smooth muscle cell proliferation and restenosis. The drug is released in controlled amounts to counteract the inflammatory response and prevent restenosis before it occurs
Solution Approach 2:
The patent creates a composite structure combining the metallic stent framework with a thin drug-containing coating layer. This composite provides both mechanical support and therapeutic anti-restenosis functionality without the drawbacks of polymer-based systems
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The stent effectively inhibits restenosis by providing a reduced stent profile, minimizing irritation, and achieving a controlled and consistent drug release, thereby improving vascular health and reducing the risk of vessel closure.
Implementation Method 1
After implantation, the bioactive agent diffuses out of the polymer matrix and preferably into the surrounding tissue.
Data Source
AI summary
A radially expandable, endovascular stent designed for placement at a site of vascular injury, for inhibiting restenosis at the site, a method of using, and a method of making the stent. The stent includes a radially expandable body formed of one or more metallic filaments and a liquid-infusible mechanical anchoring layer attached to or formed in outer surface of the filaments. A drug coating in the stent is composed of a substantially polymer-free composition of an anti-restenosis drug, and has a substratum infused in the anchoring layer and a substantially continuous surface stratum of drug that is brought into direct contact with the vessel walls at the vascular site. Thus, the rate of release of the anti-restenosis drug from the surface stratum into said vascular site is determined solely by the composition of said drug coating.