Biodegradable Polymer Blend Coating for Drug Eluting Stents

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Solution Overview

Problem

Drug eluting stents (DES) face the challenge of late thrombosis due to incomplete endothelial cell migration, which is often linked to the polymers used in their coating, necessitating prolonged anticoagulant therapy with associated risks.

Innovation Solution

A biodegradable polymer system is developed, comprising a blend of polymers with different weight average molecular weights, coated on a non-erodable metal stent, allowing for controlled release and absorption, thereby reducing the risk of late thrombosis by tailoring the bioabsorption time and incorporating bioactive agents for enhanced therapeutic effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If a polymer coating is used on DES to enable controlled drug release, then drug delivery control is improved, but bioabsorption time increases causing late thrombosis

Engineering Contradiction:

Improvebioabsorption timeVSAvoidthrombosis risk

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The patent applies parameter changes by blending polymers with different weight average molecular weights (Mw) to precisely control the bioabsorption time. By adjusting the Mw ratio (1:2 to 1:10), the polymer coating degrades at predictable rates, optimizing both drug release duration and thrombosis prevention without excessive bioabsorption time

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by creating polymer blends combining multiple polymers with different molecular weights. This composite approach allows simultaneous achievement of controlled drug release and optimized bioabsorption, resolving the contradiction between extended action duration and thrombosis risk

Inventive Principle:

Principle #40Composite materials

2Reliability

If prolonged anticoagulant therapy is administered to prevent late thrombosis, then thrombosis prevention is improved, but patient harm increases

Engineering Contradiction:

Improvethrombosis preventionVSAvoidpatient harm from anticoagulants

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs a biodegradable polymer coating that serves its protective function temporarily and then dissipates. The polymer provides thrombosis prevention during the critical healing period through controlled drug release, then absorbs away, eliminating the need for prolonged systemic anticoagulants and their associated harms

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The polymer coating provides self-contained thrombosis prevention through its controlled degradation and drug release mechanisms. The system serves its protective function autonomously during the healing period without requiring continuous external intervention via prolonged anticoagulant therapy

Inventive Principle:

Principle #25Self-service

3Reliability

If a non-polymer coated DES is used to avoid thrombosis issues, then thrombosis risk is reduced, but structural design complexity increases and controlled release becomes difficult

Engineering Contradiction:

Improvethrombosis riskVSAvoidstructural design complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent resolves this contradiction by carefully selecting and adjusting polymer parameters (molecular weight ratios) to achieve optimal performance. This allows the polymer coating to provide thrombosis prevention while maintaining relatively simple structural integration with the stent, avoiding the complexity of non-polymer alternatives

Inventive Principle:

Principle #35Parameter changes

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 biodegradable polymer system effectively reduces the risk of late thrombosis by providing a predictable degradation time and controlled release of bioactive agents, minimizing the need for prolonged anticoagulant therapy and enhancing endothelial cell growth while maintaining mechanical strength.

Implementation Method 1

The polymers are selected from the group consisting of polylactide, poylglycolide, polysaccharides, proteins, polyesters, polyhydroxyalkanoates, polyalkelene esters, polyamides, polycaprolactone, polyvinyl esters, polyamide esters, polyvinyl alcohols, modified derivatives of caprolactone polymers, polytrimethylene carbonate, polyacrylates, polyethylene glycol, hydrogels, photo-curable hydrogels, terminal diols, and combinations thereof.

Methodology Applied

Scientific EffectHydrolysis: Hydrolysis

Implementation Method 2

These bioactive agents can diffuse out of the polymer into the surrounding tissue or can be released as the polymer is degraded.

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentEP2285429B1Reducing bioabsorption time of polymer coated implantable medical devices using polymer blends

Publication Date: 2018.05.02 MEDTRONIC VASCULAR INC

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AI summary

Described herein is a system and method for reducing the risk of late thrombosis associated with drug eluting stent therapy. The stents described herein have polymeric blend coatings that can be tailored to have specific degradation times once implanted into the vasculature. The polymeric blends can have at least two polymers with different weight average molecular weights, thereby giving them degradation times that can tailored depending on the weight average molecular weights of the various polymers in the blend. The coatings can have bioactive agents dispersed on or within them which can be eluted in sync with the degradation time of the blended polymeric coating.