Hollow Wire Stent Drug Loading via Solvent Extraction
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Solution Overview
Problem
Drug-eluting medical devices face challenges in controlling the rate of drug elution and delivering increased quantities of therapeutic agents due to limitations in polymer coatings, which can cause adverse reactions and prevent drug delivery to the target site.
Innovation Solution
A method for loading a therapeutic substance into the lumen of a hollow wire stent with side openings, allowing for controlled drug release through reverse or forward filling and solvent extraction, enabling improved control over elution rates and quantities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer coatings are used to deliver drugs, then the drug can be delivered to the target site, but the polymer may cause adverse reactions and form clots
Solution Approach 1:
The patent removes the polymer coating entirely from the stent structure, extracting the harmful element while preserving the drug delivery function. The drug is delivered directly through the metal stent struts without any polymer intermediary, eliminating the source of adverse reactions and clot formation while maintaining therapeutic efficacy.
Solution Approach 2:
The patent introduces a novel intermediary mechanism where the metal stent strut itself serves as the drug delivery medium. Instead of using polymer as an intermediary between the metal stent and the drug, the metal surface directly interacts with and releases the therapeutic agent, eliminating the harmful polymer mediator while maintaining drug delivery functionality.
2Duration of action of moving object
If polymer coatings are used to control drug elution, then the drug release rate can be controlled, but the quantity of drug that can be delivered is limited by the coating capacity and device size
Solution Approach 1:
The patent transitions from a two-dimensional surface coating approach to a three-dimensional integrated structure where the drug is incorporated throughout the volume of the stent struts. This dimensional change allows significantly increased drug loading capacity while maintaining controlled release kinetics through the stent structure.
Solution Approach 2:
The patent creates a composite structure where the metal stent material is integrated with the drug formulation at the molecular level. This composite approach allows the metal substrate to serve both structural and drug delivery functions, dramatically increasing the total drug carrying capacity compared to separate polymer coating systems.
3Adaptability or versatility
If polymer coatings are applied to stents, then the stent can provide structural support and drug delivery, but the coatings may flake off or be damaged during delivery
Solution Approach 1:
The patent merges the structural support function and drug delivery function into a single integrated metal stent structure. By combining these functions into one monolithic component rather than separate layers, the design eliminates the interface between structural and therapeutic elements, preventing delamination and coating damage during delivery while maintaining both functionalities.
Solution Approach 2:
The patent extracts and removes the polymer coating layer that causes reliability issues during delivery. By taking out the separate coating component and integrating its drug delivery function directly into the metal stent structure, the design eliminates the risk of coating flaking or damage while preserving the dual functionality of structural support and drug 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
This approach allows for controlled and increased delivery of therapeutic agents, reducing adverse reactions and ensuring effective drug distribution to the target site, achieving similar clinical efficacy to polymer-coated stents while minimizing polymer-related complications.
Implementation Method 1
a solvent or dispersion medium extracting step is performed to extract the solvent or dispersion medium from within the lumenal space
Implementation Method 2
the solvent is sublimated
Data Source
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AI summary
Methods and apparatus are disclosed for loading a therapeutic substance or drug within a lumenal space of a hollow wire having a plurality of side openings along a length thereof that forms a hollow drug-eluting stent with a plurality of side drug delivery openings. Loading a drug within the lumenal space of the hollow stent includes a drug filling step, in which the drug is mixed with a solvent or dispersion medium. The lumenal space may be filled with the drug solution or suspension in a reverse fill process and/or a forward fill process. After the drug filling step, a solvent or dispersion medium extracting step is performed to extract the solvent or dispersion medium from within the lumenal space such that only the drug remains within the hollow stent. A stent cleaning step may be performed to an exterior surface of the hollow stent.