Drug Eluting Stent Coatings with Layered Particles
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Solution Overview
Problem
Current drug-coated stents face challenges in delivering hydrophobic or hydrophilic therapeutic agents effectively due to the hydrophobic or hydrophilic nature of the coatings, leading to uneven distribution and release of drugs, particularly with paclitaxel, which clusters within the coating and fails to release consistently in different environments.
Innovation Solution
The development of medical devices with coatings comprising particles having alternating hydrophilic and hydrophobic layers, allowing for a microenvironment that enables efficient and consistent release of therapeutic agents, such as paclitaxel, by using biodegradable polymeric materials like polyvinyl alcohol (PVA) and poly(L-lactide) (PLLA) for hydrophilic coatings and copolymers of styrene and isobutylene for hydrophobic coatings, ensuring sustained release over a defined period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a hydrophobic coating is used to deliver a hydrophobic drug like paclitaxel, then the drug can be incorporated into the coating, but the drug will cluster inside the coating and not be evenly distributed
Solution Approach 1:
The coating is segmented into multiple layers with different hydrophobicity levels (hydrophobic outer layer, intermediate layer, hydrophilic inner layer). This segmentation allows the hydrophobic drug to be distributed throughout the coating structure rather than clustering in one region, while still maintaining drug incorporation capability.
Solution Approach 2:
Different regions of the coating have different local properties (hydrophobicity levels). The outer layers are hydrophobic to accept the hydrophobic drug, while the inner layer is hydrophilic to enable drug release into the aqueous environment. This local quality variation resolves the contradiction between drug incorporation and uniform distribution.
2Quantity of substance
If a hydrophobic coating is used to deliver a hydrophobic drug, then the drug can be incorporated into the coating, but it is difficult to get 100% release of the drug into a hydrophilic environment
Solution Approach 1:
The coating is divided into layers with progressively different hydrophobicity, creating a gradient that facilitates drug transport from the hydrophobic outer regions to the hydrophilic inner layer, enabling complete drug release while maintaining incorporation.
Solution Approach 2:
The intermediate layer acts as a mediator between the hydrophobic outer layer and the hydrophilic inner layer. This intermediate hydrophobicity gradient facilitates the transfer of the hydrophobic drug from the coating into the aqueous environment, resolving the release efficiency problem.
3Productivity
If a hydrophilic coating is used, then the coating can release drugs into the aqueous environment, but hydrophobic drugs will cluster inside the coating and not be evenly distributed
Solution Approach 1:
The coating is segmented into multiple layers with different hydrophobicity levels. The outer hydrophobic layers ensure uniform drug distribution during incorporation, while the inner hydrophilic layer ensures efficient release into the aqueous environment.
Solution Approach 2:
The coating uses a composite structure combining hydrophobic and hydrophilic materials in specific layers. This composite approach allows the coating to simultaneously provide uniform drug distribution (via hydrophobic outer layers) and efficient drug release (via hydrophilic inner layer).
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
This approach allows for uniform and sustained release of therapeutic agents, improving the delivery of drugs like paclitaxel, reducing restenosis and stenosis by inhibiting cell proliferation and migration, while being biocompatible and adaptable to different environments.
Implementation Method 1
The coatings as well as the outer layers and inner layers of the particles are preferably biodegradable and capable of providing sustained release of the one or more therapeutic agents over a time period
Implementation Method 2
The development of medical devices with coatings comprising particles having alternating hydrophilic and hydrophobic layers, allowing for a microenvironment that enables efficient and consistent release of therapeutic agents
Data Source
AI summary
The present invention relates generally to medical devices, preferably a stent, having a drug eluting surface coated or covered with a coating of particles comprising at least an outer layer, an inner layer, and a core comprising a therapeutic agent. Specifically, the invention relates to medical devices having a hydrophilic coating comprising particles with a hydrophilic outer layer, a hydrophobic inner layer, and a core comprising a hydrophobic therapeutic agent, as well as medical devices having a hydrophobic coating comprising particles with a hydrophobic outer layer, a hydrophilic inner layer, and a core comprising a hydrophilic therapeutic agent. The coating, outer layer, and inner layer are preferably biodegradable and capable of providing sustained release of the therapeutic agent over a time period. The invention also relates to methods of making and methods of using the coated or covered medical device.