Hydrogel Contact Lens Cationic Agent Loading via pH Shift
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Solution Overview
Problem
Existing methods for manufacturing contact lenses that administer beneficial agents are inefficient, requiring excessive drug amounts, causing lens dimension changes upon agent release, and are complex, making them unsuitable for high-volume manufacturing.
Innovation Solution
A method involving polymerizing a monomer mixture with carboxylic acid-containing monomers to form a hydrogel contact lens, which is then packaged in a solution with a beneficial cationic agent and autoclaved, utilizing a buffer with reduced ionic strength and temperature-sensitive properties to enhance agent uptake and release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If prior art methods are used to manufacture contact lenses for delivering beneficial agents, then the lens can deliver the agent to ocular tissue, but significantly more drug is required to make the lens than is actually delivered to the patient
Solution Approach 1:
The contact lens is pre-loaded with the beneficial agent during manufacturing by immersing the lens in a packaging solution containing the agent, allowing the lens to absorb and store the agent before use. This preliminary loading ensures optimal agent concentration is achieved without waste during the delivery process.
2Duration of action of moving object
If prior art methods are used to manufacture contact lenses for delivering beneficial agents, then the lens can deliver the agent to ocular tissue, but the dimensions or physical properties of the lens may significantly change upon release of the agent
Solution Approach 1:
The patent utilizes temperature-sensitive packaging solutions that change pH during autoclaving (e.g., pH drops from 7.5 to 6.5), which facilitates agent uptake by the lens while maintaining lens structural integrity. The controlled parameter changes during manufacturing ensure stable lens properties during agent loading.
3Reliability
If prior art methods are used to manufacture contact lenses for delivering beneficial agents, then the lens can deliver the agent to ocular tissue, but the methods are complex and not amenable to high volume manufacturing operations
Solution Approach 1:
The patent combines multiple functions into a single packaging solution: it serves as both the storage medium for the beneficial agent and the delivery vehicle for loading the agent into the lens. The solution contains buffering agents and stabilizing agents that simultaneously maintain pH, prevent degradation, and facilitate agent uptake, simplifying the manufacturing process for high-volume production.
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 method increases cationic agent uptake by the lens, maintains dimensional stability, and facilitates efficient and stable release, while being amenable to high-volume manufacturing.
Implementation Method 1
The beneficial cationic agent ionically binds to the carboxylic acid groups of the polymerization product and releases from the contact lens upon wear by a patient
Implementation Method 2
the packaging solution is temperature-sensitive, meaning that its pH drops by at least one during autoclave at 120°C for 30 minutes
Data Source
AI summary
Contact lenses comprising an ionic component are packaged with a beneficial cationic agent in a temperature-sensitive packaging solution and/or a low ionic strength packaging solution.