Implantable Polymer Depots With Diffusion Openings for Sustained Release
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Solution Overview
Problem
Existing implantable drug delivery systems lack a controlled, sustained release mechanism, often resulting in a burst release of therapeutic agents upon contact with physiologic fluids, which can be undesirable for clinical applications requiring prolonged and localized drug delivery.
Innovation Solution
A biocompatible implantable depot comprising a therapeutic region with an analgesic and a bioresorbable polymer mixed with a releasing agent, configured to form diffusion openings in vivo, allowing for controlled and sustained release of the analgesic over an extended period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If hydrophilic polymers are added as wetting agents to accelerate drug release, then immediate release of hydrophobic drug is enhanced, but controlled sustained release is lost
Solution Approach 1:
The polymer carrier is segmented into distinct functional regions: a hydrophobic polymer matrix for drug loading and a hydrophilic outer layer for controlled release. This segmentation allows the inner region to provide sustained release while the outer layer facilitates controlled drug diffusion, resolving the contradiction between rapid release and sustained duration.
Solution Approach 2:
Different regions of the polymer carrier have different material properties: the inner core uses hydrophobic polymer for high drug loading and sustained release, while the outer layer uses hydrophilic polymer for controlled drug diffusion. This local differentiation of material properties enables simultaneous achievement of both rapid initial release and sustained duration.
2Object-affected harmful factors
If biocompatible polymer carriers are used for localized delivery, then systemic side effects are avoided, but controlled release mechanism is insufficient
Solution Approach 1:
The polymer carrier is pre-formed with a specific双层 structure during manufacturing, creating a hydrophobic core and hydrophilic outer layer before implantation. This preliminary structural preparation ensures that upon implantation, the device automatically provides controlled release without requiring additional control mechanisms, thereby improving reliability while maintaining localized delivery.
Solution Approach 2:
The hydrophilic outer layer acts as an intermediary between the hydrophobic drug core and the aqueous physiological environment. This intermediary layer controls the diffusion of drug molecules to surrounding tissues, providing reliable controlled release while maintaining the biocompatibility and localized delivery advantages of the polymer carrier.
3Quantity of substance
If large dose of therapeutic agent is implanted, then treatment effectiveness is improved, but burst release of drug is increased
Solution Approach 1:
The polymer carrier is designed with spatial differentiation of material properties: a large-volume hydrophobic core for high drug loading (achieving large dose) and a controlled-release hydrophilic outer layer that prevents burst release by regulating drug diffusion. This local quality differentiation allows high dose implantation without compromising safety.
Solution Approach 2:
The polymer carrier is pre-formed with a controlled双层 structure during manufacturing, creating a hydrophobic core and hydrophilic outer layer before implantation. This preliminary structural preparation ensures that upon implantation, even large doses of therapeutic agent are released in a controlled manner without burst release, thereby improving treatment effectiveness while maintaining safety.
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 depot provides a highly controlled release of the analgesic, with a significant portion released over 11 days following an initial controlled release phase, minimizing systemic side effects and ensuring effective treatment at the implant site.
Implementation Method 1
a releasing agent configured to dissolve when the implant is placed in contact with a fluid to form diffusion openings in the control region
Implementation Method 2
form diffusion openings in the control region... release the analgesic through the diffusion openings
Data Source
AI summary
The present technology relates to depot assemblies for the controlled, sustained release of a therapeutic agent. The assembly can include a depot having a therapeutic region comprising a therapeutic agent, and a control region comprising a bioresorbable polymer and a releasing agent mixed with the polymer. The releasing agent may be configured to dissolve when the depot is placed in vivo to form diffusion openings in the control region. The depot may be configured to be implanted at a treatment site in vivo and, while implanted, release the therapeutic agent at the treatment site for no less than 3 days.