Drug Eluting Stent Coating for Localized Tissue Delivery
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Solution Overview
Problem
Current drug-eluting stents for peripheral vascular interventions face challenges such as inadequate drug delivery, high systemic drug concentrations leading to adverse effects, and stent fracture, which result in reduced efficacy and increased risk of restenosis.
Innovation Solution
A polymer/drug-coated stent design that controls drug elution to preferentially deliver the drug to vascular tissue while maintaining low systemic concentrations, using a stent body made of superelastic alloys like nitinol with a polymeric coating that forms a diffusion pathway for lipophilic or amphipathic drugs like everolimus, ensuring prolonged therapeutic effects and minimizing systemic exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If drug-eluting stents are used with high drug loads and fast elution, then adequate drug delivery to tissue is achieved, but systemic drug concentrations become excessively high causing adverse effects
Solution Approach 1:
The patent applies local quality by creating a hydrophobic microenvironment at the stent-tissue interface through hydrophobic components (such as hydrophobic polymers or surfactants). This localized hydrophobicity preferentially attracts and delivers lipophilic drugs to the tissue while preventing systemic absorption, thus achieving high local drug delivery without excessive systemic exposure
Solution Approach 2:
The patent uses hydrophobic components as intermediaries between the drug and the biological environment. These intermediaries create a preferential partitioning pathway that directs drug delivery to the tissue while blocking the aqueous blood pathway, effectively mediating selective drug transport
2Duration of action of moving object
If drug elution is prolonged to maintain therapeutic levels, then restenosis prevention is improved, but the risk of cumulative systemic toxicity increases
Solution Approach 1:
The sustained hydrophobic microenvironment created by the patent enables prolonged local drug residence at the tissue interface. The hydrophobic components continuously partition drug to the tissue over extended periods without allowing significant systemic entry, thus achieving long-duration therapy without cumulative systemic toxicity
3Strength
If stent structure is made more flexible to prevent fracture, then structural integrity is improved, but drug coating stability may be compromised
Solution Approach 1:
The patent employs composite materials by combining hydrophobic components (polymers or surfactants) with the drug and stent structure. This composite approach creates a multi-functional system where the hydrophobic matrix provides both mechanical flexibility to prevent fracture and chemical stability to maintain drug coating integrity over time
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 design achieves enhanced drug delivery to the target tissue with reduced systemic drug concentrations, thereby inhibiting occlusion, stenosis, and restenosis, while maintaining structural integrity to prevent fracture.
Implementation Method 1
The polymeric coating and drug are configured to cooperate so as to form a lipophilic diffusion pathway with tissue when the stent is disposed in a body lumen
Implementation Method 2
The stent body can be made of superelastic nitinol
Data Source
AI summary
A drug eluting stent can include a stent body having a polymeric coating with a lipophilic and/or hydrophilic element. A drug that has a bioactivity that inhibits cell proliferation can be disposed in the polymeric coating. The drug can be present in the polymer at an amount greater than or equal to about 150 μg/cm2. The polymeric coating and drug are configured to cooperate so as to form a diffusion pathway with tissue when the stent is disposed in a body lumen such that the drug preferentially diffuses into the tissue over a body fluid passing through the body lumen such that a maximum systemic blood concentration of the drug is less than about 40 ng/ml.