Electrostatic Primer for Stent Drug Adhesion
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Solution Overview
Problem
Conventional stents with surface coatings for delivering beneficial agents face issues such as suboptimal drug release kinetics, increased trauma during implantation, mechanical failure, and limited control over the delivery of multiple drugs, which contribute to restenosis and thrombosis complications.
Innovation Solution
An implantable medical device with a primer coating having an opposite electric charge to the antithrombotic agent coating, used as an intermediate layer between the antithrombotic agent and therapeutic agents in openings of the stent, enhances the adhesion and controlled release of therapeutic agents without increasing the stent's wall thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a surface coating of therapeutic agents is applied to the stent, then drug delivery capability is improved, but the coating thickness must be kept thin (5-8 microns) to avoid increasing stent wall thickness, which limits the volume of beneficial agent and control over release kinetics
Solution Approach 1:
The patent applies nesting by placing the therapeutic agent coating inside the stent struts (within the metal structure) rather than on the external surface. This allows the coating to be housed within the existing stent geometry, increasing the effective volume for drug loading without increasing the overall stent wall thickness or external dimensions.
Solution Approach 2:
The patent transitions from surface coating (2D) to volumetric coating within the strut structure (3D). By moving the therapeutic agent delivery from a thin surface layer to a three-dimensional space within the struts, the patent increases drug volume and enables better control over release kinetics while maintaining the same external stent dimensions.
2Quantity of substance
If a surface coating of therapeutic agents is applied to the stent, then drug delivery capability is improved, but the coating is vulnerable to mechanical failure or damage during expansion and implantation
Solution Approach 1:
By nesting the therapeutic agent coating within the stent strut structure, the coating is protected by the surrounding metal structure during expansion and implantation. This internal positioning shields the coating from mechanical damage that would occur if it were on the external surface subjected to expansion forces.
Solution Approach 2:
The patent provides protective structuring before the coating is subjected to mechanical stresses. The stent strut structure is designed to accommodate and protect the therapeutic agent coating during the expansion process, preventing mechanical failure before implantation occurs.
3Duration of action of moving object
If conventional surface coatings are used, then drug delivery is achieved, but control over release kinetics is limited resulting in large initial burst followed by rapid approach to asymptote rather than uniform prolonged release
Solution Approach 1:
The patent enables precise control over release kinetics by transitioning from thin surface coating to volumetric coating within the struts. This three-dimensional configuration allows manipulation of drug concentration gradients, diffusion paths, and release rates, achieving uniform prolonged release rather than the burst kinetics characteristic of thin surface coatings.
Solution Approach 2:
The patent controls release kinetics by changing physical parameters including coating thickness, drug concentration, and spatial distribution within the strut structure. These parameter variations enable tailored release profiles with sustained, uniform delivery over extended periods.
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 primer coating improves the adhesion and controlled release of therapeutic agents, reducing restenosis and thrombosis risks by allowing for tailored drug distribution and prolonged release profiles, while maintaining the stent's mechanical properties.
Implementation Method 1
a primer coating (200) having an opposite electric charge to the antithrombotic agent coating (100)
Data Source
AI summary
An expandable medical device includes a plurality of elongated struts, forming a substantially cylindrical device which is expandable from a first diameter to a second diameter. A plurality of different beneficial agents may be loaded into different openings within the struts for delivery to the tissue. For treatment of conditions such as restenosis, different agents are loaded into different openings in the device to address different biological processes involved in restenosis and are delivered at different release kinetics matched to the biological process treated. The different agents may also be used to address different diseases from the same drug delivery device. In addition, anti-thrombotic agents may be affixed to at least a portion of the surfaces of the medical device for the prevention of sub-acute thrombosis. To ensure that the different agents remain affixed to the device as well as to each other, primer layers may be utilized.