Contact Lenses with Diffusion Attenuators for Sustained Drug Release
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for ocular drug delivery through contact lenses suffer from burst release, where most of the bioactive agent is released quickly, leading to negligible release over extended periods, and existing solutions like diffusion-controlled coatings can alter surface properties and complicate lens design.
Innovation Solution
Incorporating diffusion attenuators, such as liquid or solid particles, into the contact lens material to modify molecular diffusivity and create a tortuous path for bioactive agents, allowing for sustained release over 8 hours or more without impacting surface properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a diffusion-controlled coating is placed on the surface of a lens to control drug release, then the release duration can be extended, but the surface properties such as wettability, protein binding, and lubricity are altered with undesirable consequences
Solution Approach 1:
The patent extracts the diffusion control function from the lens surface coating and relocates it to the lens bulk material by incorporating diffusion attenuators (particles or aggregates) throughout the lens matrix. This separates the surface properties (wettability, lubricity) from the drug release control mechanism, allowing the surface to remain optimized for ocular comfort while the bulk material controls diffusion timing.
Solution Approach 2:
The patent introduces diffusion attenuators (particles or aggregates of polymer, lipid, or other materials) as intermediary elements within the lens bulk that specifically modulate drug diffusion without affecting surface properties. These attenuators act as mediators that selectively interact with the drug molecule to control its release kinetics while leaving the lens surface characteristics unchanged.
2Duration of action of moving object
If a thick diffusion barrier layer is deposited on the lens surface to significantly alter drug transport, then the release duration increases, but the transparency and mechanical properties of the lens are adversely impacted
Solution Approach 1:
The patent applies local quality by distributing diffusion attenuators heterogeneously throughout the lens bulk material rather than creating a uniform thick surface coating. This allows diffusion control to be achieved through cumulative effect of many small dispersed particles, maintaining lens transparency and mechanical integrity while still significantly extending drug release duration.
Solution Approach 2:
The patent utilizes porous or aggregated particle structures as diffusion attenuators that provide tortuous diffusion paths for drug molecules. These porous materials (such as cross-linked polymer networks or aggregated particles) create maze-like pathways that extend diffusion time without requiring thick surface layers, thereby preserving lens optical and mechanical properties.
3Duration of action of moving object
If multiple diffusion barrier layers are constructed to control drug release, then the release profile can be optimized, but the fabrication process becomes complicated
Solution Approach 1:
The patent merges multiple diffusion control functions into a single lens fabrication step by incorporating diffusion attenuators directly into the lens bulk material during manufacturing. Instead of requiring separate coating and assembly steps for multiple barrier layers, the attenuators are integrated into the lens matrix itself, simplifying fabrication while achieving complex release profiles through the distribution and composition of the embedded particles.
Solution Approach 2:
The patent creates a universal lens structure that can control drug release for multiple different bioactive agents by using diffusion attenuators with adjustable properties (size, composition, concentration). A single lens design approach can be adapted to control release of various drugs with different molecular characteristics, eliminating the need for complex multi-layer structures tailored to each specific drug.
4Duration of action of moving object
If the bulk material is changed to one of different diffusivity to increase release duration, then the diffusion control is achieved, but the contact lens material selection is limited by strict requirements and many material properties cannot be compromised
Solution Approach 1:
The patent segments the diffusion control function from the bulk material selection by embedding discrete diffusion attenuator particles within the lens matrix. This allows the bulk lens material to be selected based on optimal optical, mechanical, and comfort properties, while the diffusion control is achieved through the separate, adjustable parameters of the embedded particles (size, concentration, composition), providing versatility for different drug release requirements.
Solution Approach 2:
The patent achieves diffusion control by changing parameters of the embedded attenuators (particle size, concentration, composition, cross-linking density) rather than changing the bulk lens material itself. This allows independent optimization of lens material properties for comfort and optics, while diffusion release duration is controlled by adjusting attenuator parameters, providing material selection flexibility.
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 use of diffusion attenuators in contact lenses extends the release duration of bioactive agents, providing a more controlled and sustained delivery of drugs like dexamethasone, timolol, and Vitamin E, maintaining optical clarity and mechanical properties.
Implementation Method 1
The release of a bioactive agent or any other compound from a contact lens is ultimately controlled by diffusion within the lens material. For a diffusion controlled process, the duration of release can be approximately calculated by l2/D, where l is the path length that a compound needs to traverse and D is the molecular diffusivity.
Implementation Method 2
The diffusion attenuator can be any combination of a liquid that modifies the molecular diffusivity, D, of the lens material or a plurality of phase separated liquid aggregates or solid particles dispersed to act as barriers to the diffusion of one or more bioactive agents included within the lens. As a diffusion barrier the path length, l, is changed from that of the unmodified lens.
Data Source
AI summary
An appliance for the delivery of at least one bioactive agent to the eye has at least one diffusion attenuator within a hydrophilic or silicone-hydrogel contact lens. The bioactive agent can be a drug or a nutraceutical. The diffusion attenuator can be a plurality of solid particles or phase separated liquid aggregates within at least one continuous phase of the lens where the diffusion attenuators promote a tortuous path for the diffusion of the bioactive agent to mediate the rate by which the bioactive agent diffuses from the contact lens. The diffusion attenuator can be homogeneously dispersed throughout at least one continuous phase of the lens to modify the diffusivity of the bioactive agent through that phase. The diffusion attenuator can have little or no affinity for the bioactive agent or can be miscible with the bioactive agent. The diffusion attenuator can be incorporated while forming the contact lens by polymerization of a monomer mixture containing the diffusion attenuator. For liquid diffusion attenuators, the liquid can be co-absorbed with a solvent into the lens followed by removal of the solvent, where the bioactive agent can be co-absorbed or subsequently absorbed after the loading of the diffusion attenuator. The diffusion attenuator can be Vitamin E.