Stent Graft Lubricious Coating and Drug Release
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Solution Overview
Problem
Implantable stent grafts face challenges in maintaining mechanical integrity during radial compression and ensuring sustained release of therapeutic agents, particularly in treating biliary tract cancers, where existing solutions fail to provide effective delivery and retention of therapeutic agents due to friction issues and inadequate release profiles.
Innovation Solution
The development of stent grafts with a radially expandable support frame and a synthetic graft material containing a releasable therapeutic agent, where the concentration of the agent is increased to slow release at body temperature, and a lubricious polymer coating is used to reduce friction during deployment, allowing for sustained release of chemotherapeutic agents like paclitaxel within a body vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stent graft is compressed radially for delivery, then the device can be inserted through catheters, but the graft material experiences increased friction and potential damage
Solution Approach 1:
A lubricious coating layer is applied to the outer surface of the graft material to serve as an intermediary between the graft and the delivery catheter. This coating reduces friction during radial compression and delivery, allowing the stent graft to be inserted through catheters without damaging the graft material or experiencing excessive friction forces
2Duration of action of moving object
If the therapeutic agent concentration is increased in the graft material, then the release duration is extended, but the initial release rate may be affected
Solution Approach 1:
The concentration of therapeutic agent in the graft material is adjusted to optimize the release profile. By changing the drug loading concentration parameter, the system achieves sustained release over the desired duration while maintaining an appropriate initial release rate for therapeutic efficacy
Solution Approach 2:
The release system is designed to dynamically adjust the release rate over time. The graft material composition and structure are engineered to provide an initial burst release followed by sustained release, creating a dynamic release profile that maintains therapeutic levels throughout the desired duration
3Ease of operation
If a lubricious coating is applied to reduce friction, then the delivery process is improved, but the coating must not interfere with therapeutic agent release
Solution Approach 1:
The graft structure is segmented into distinct functional layers: an inner layer containing the therapeutic agent and an outer lubricious coating layer. This segmentation allows each layer to perform its specific function independently - the inner layer ensures reliable drug release while the outer layer provides friction reduction during delivery
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 solution enables stent grafts to maintain mechanical integrity during deployment and achieve a sustained release of therapeutic agents, effectively treating biliary tract tumors by ensuring a therapeutically effective dose of paclitaxel is released over an extended period, improving treatment efficacy.
Implementation Method 1
a lubricious polymer coating is used to reduce friction during deployment
Implementation Method 2
the concentration of the agent is increased to slow release at body temperature
Implementation Method 3
releasing the therapeutic agent more slowly at temperatures approaching body temperature
Data Source
AI summary
Medical devices for implantation within a body vessel comprising a graft material and a releasable therapeutic agent are provided. The graft material preferably comprises a biocompatible polyurethane and a therapeutic agent. Preferably, the medical device is a stent graft formed by attaching a polyurethane graft material comprising an elutable taxane therapeutic agent to a radially expandable frame.