Stent Coating with Parylene Primer for Drug Stability
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Solution Overview
Problem
Current methods for preventing restenosis after percutaneous transluminal coronary angioplasty are ineffective, as systemic pharmacologic agents fail to achieve therapeutic concentrations without reaching toxic levels, and there is a need for a stable and effective way to deliver therapeutic agents directly to the site of vascular injury to prevent intimal thickening and restenosis.
Innovation Solution
A process for coating implantable medical devices, such as stents, with a primer layer of parylene, followed by a basecoat solution of biocompatible polymers and therapeutic agents, and a topcoat solution, all applied in a manner that minimizes exposure to oxygen and free radicals to stabilize the therapeutic agent and ensure its release in therapeutic dosages over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If systemic pharmacologic agents are used to prevent restenosis, then therapeutic effect is achieved, but toxic side effects occur due to inability to achieve therapeutic concentrations without reaching toxic levels
Solution Approach 1:
The patent applies local quality by delivering therapeutic agents directly to the site of vascular injury through stent coating, rather than using systemic pharmacologic agents. The coating contains anti-proliferative agents that are released locally at the injury site, achieving therapeutic concentrations without the toxic side effects associated with systemic drug administration.
Solution Approach 2:
The stent coating acts as an intermediary delivery system between the therapeutic agent and the injured vascular tissue. The coating matrix serves as a reservoir that releases the anti-proliferative agent locally, mediating the interaction between the drug and target tissue while avoiding systemic circulation.
2Reliability
If therapeutic agents are coated on stents, then direct delivery to injured tissue is achieved, but agent stability is compromised due to exposure to oxygen and free radicals
Solution Approach 1:
The patent employs an inert atmosphere principle by using oxygen-scavenging materials within the coating formulation. These materials create a protective microenvironment that depletes oxygen and prevents oxidation of the therapeutic agent, thereby maintaining agent stability during storage and deployment.
Solution Approach 2:
The patent converts the harmful effect of oxygen exposure into a beneficial protective mechanism by incorporating oxygen-scavenging materials. These materials actively consume oxygen and free radicals that would otherwise degrade the therapeutic agent, transforming the potential harm of oxidation into a protective antioxidant effect.
3Ease of manufacture
If coating process exposes materials to oxygen and free radicals, then coating application is simplified, but autoxidation occurs reducing therapeutic agent stability
Solution Approach 1:
The patent converts the harmful autoxidation process into a beneficial protective mechanism by incorporating oxygen-scavenging materials. These materials actively consume oxygen and free radicals during the coating process and storage, preventing degradation of the therapeutic agent while allowing relatively simple coating manufacturing processes.
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 process enhances the stability of therapeutic agents, reduces autoxidation, and maintains effective drug delivery, potentially reducing restenosis by providing sustained release of anti-proliferative agents directly to the injured vascular tissue.
Implementation Method 1
applying a primer coating on the implantable medical devices, including the application of a parylene layer and annealing the parylene layer to reduce autoxidation initiators
Implementation Method 2
annealing the parylene layer to reduce autoxidation initiators
Implementation Method 3
applying a solvent that has the potential to redissolve all coating components, creating a coating morphology to protect the therapeutic agent from autoxidation
Implementation Method 4
preparing the basecoat solution with and applied utilizing a process to reduce the presence and exposure of the basecoat solution to oxygen
Implementation Method 5
processing the implantable medical devices, including inspecting, packaging and sterilizing the coated medical devices, the final processing including protecting the therapeutic agent from autoxidation, reducing the presence of and exposure of all materials to free radicals and reducing the presence of and exposure of all materials to oxygen
Data Source
AI summary
Processes for coating implantable medical devices that improve the stability of therapeutic agents contained within the coating.