Surface-Eroding Polymer Coating for Controlled Drug Release
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Solution Overview
Problem
Bulk-eroding biodegradable polymers used in implantable medical devices often exhibit complex and unpredictable drug release profiles due to simultaneous internal degradation, leading to burst releases of therapeutic agents, which can be detrimental to patient health.
Innovation Solution
A method is developed to manipulate the surface area to volume ratio of biodegradable polymer layers on medical devices to exhibit surface erosion characteristics, using a high surface area to volume ratio and specific polymer compositions like poly(L-lactide) and polyglycolide, along with a therapeutic agent, to control drug release, mimicking surface-eroding polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If bulk-eroding biodegradable polymers are used in implantable medical devices, then the polymer degrades in the body, but the drug release profile becomes complex and unpredictable with burst releases
Solution Approach 1:
The patent changes the surface area to volume ratio parameter of the polymer coating to achieve surface-eroding characteristics. By controlling the coating thickness and device geometry, the surface area to volume ratio is optimized to enable predictable linear drug release rather than burst release, thus resolving the contradiction between polymer degradation and reliable drug release control
Solution Approach 2:
The patent uses composite material structures combining the biodegradable polymer coating with the medical device substrate. This composite approach allows the polymer layer to exhibit surface-eroding behavior while maintaining device integrity, achieving both degradation functionality and controlled drug release
2Quantity of substance
If the polymer layer thickness is increased, then more drug can be loaded, but the drug release becomes less controlled and burst releases occur
Solution Approach 1:
The patent transitions from controlling drug release through bulk polymer properties to controlling it through surface geometry. By optimizing the surface area to volume ratio of the coating layer, the system achieves controlled release kinetics while maintaining adequate drug loading capacity, resolving the contradiction between quantity and control
3Reliability
If surface-eroding polymers are used, then controlled linear drug release is achieved, but the surface area to volume ratio must be precisely controlled
Solution Approach 1:
The patent identifies and controls key parameters including coating thickness, device geometry, and polymer composition to achieve the desired surface area to volume ratio. By establishing specific parameter ranges and relationships, the system achieves surface-eroding behavior with manufacturable precision
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 results in a controlled, linear drug release profile, reducing the risk of burst releases and enhancing the biocompatibility and efficacy of therapeutic agents, such as everolimus, by converting bulk-eroding polymers to exhibit surface-eroding behavior, thereby improving the safety and effectiveness of localized drug delivery.
Implementation Method 1
surface-eroding polymers... mass loss at the polymer surface to be greater than mass loss caused by ingress of water into the polymer bulk
Implementation Method 2
the predominant mechanism by which a drug will escape the reservoir is by simple passive diffusion from the polymer matrix
Implementation Method 3
with or without prior swelling of the polymer due to exposure to bodily fluids
Implementation Method 4
Bulk-eroding biodegradable polymers... water compatible polymers absorb water and along with it the enzymes and other biodegradation-causing components of a physiological system. The absorbed components cause internal degradation of the polymer
Data Source
AI summary
The present invention relates to an implantable medical device comprising therapeutic agents coated on the device using polyesters for the drug reservoir layer that exhibit surface-eroding characteristics.