Preservative Removal from Eye Drops Using Hydrogel Plug
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Solution Overview
Problem
Current eye drop formulations face contamination risks due to preservative toxicity, particularly from benzalkonium chloride (BAK), which can cause ocular damage and irritation, despite its antimicrobial efficacy.
Innovation Solution
A preservative removing device featuring a plug of hydrophilic polymeric gel, specifically poly(hydroxyethyl methacrylate) (pHEMA), that selectively absorbs BAK from eye drop solutions, ensuring the eye drops dispensed are preservative-free while maintaining the sterility of the bottle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If benzalkonium chloride (BAK) is added to eye drop formulations to achieve regulatory antimicrobial effectiveness, then the antimicrobial and antifungal effects are improved, but toxic side effects to the cornea occur
Solution Approach 1:
The patent extracts BAK from the eye drop formulation by incorporating it into a biocompatible polymer matrix (such as hydrogels or microparticles) that is retained in the bottle, while allowing the preservative-free solution to be dispensed. This separation removes the harmful preservative from the administered drops while maintaining its antimicrobial function in the bottle.
Solution Approach 2:
The patent applies different functional properties to different parts of the system: the polymer matrix containing BAK remains in the bottle to provide antimicrobial protection, while the preservative-free solution contacts the eye. This local differentiation allows BAK to exert its antimicrobial effect where needed (in the bottle) without causing ocular toxicity.
2Reliability
If preservatives are added to multi-dose eye drop formulations to prevent contamination, then the risk of cross-contamination is reduced, but the potential for ocular damage increases
Solution Approach 1:
The patent extracts the preservative from the dispensable solution and confines it to the polymer matrix in the bottle. This allows the solution to be preservative-free and safe for ocular contact, while the polymer matrix with embedded preservative maintains contamination prevention capabilities in the bottle.
Solution Approach 2:
The biocompatible polymer matrix acts as an intermediary that carries the preservative function without directly contacting the ocular surface. The polymer serves as a carrier that releases or presents the antimicrobial agent in the bottle environment while preventing its harmful contact with eye tissues.
3Reliability
If BAK is used at concentrations required for regulatory effectiveness, then the antimicrobial efficacy is achieved, but the toxic side effects to ocular tissues increase
Solution Approach 1:
The patent removes BAK from the dispensable eye drop solution while retaining it in the polymer matrix in the bottle. This extraction allows the administered drops to be completely free of BAK, eliminating all concentration-related toxic effects while the bottle maintains adequate preservative levels for efficacy.
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 device effectively removes at least 50% of BAK from eye drop solutions, reducing ocular toxicity and maintaining the antimicrobial properties of the preservative within the bottle, thus addressing the contamination and toxicity issues associated with BAK.
Implementation Method 1
The plug has a shape that matches an outlet to a container for a solution, emulsion, or suspension. The hydrophilic polymeric gel swells in the presence of the solution, emulsion, or suspension and selectively absorbs a preservative contained therein.
Implementation Method 2
The hydrophilic polymeric gel swells in the presence of the solution, emulsion, or suspension and selectively absorbs a preservative contained therein.
Data Source
AI summary
A BAK removal device is constructed as a plug of microparticles of a hydrophilic polymeric gel that displays a hydraulic permeability greater than 0.01 Da. The polymer hydrophilic polymeric gel comprises poly(2-hydroxyethyl methacrylate) (pHEMA). The particles are 2 to 100 μm and the plug has a surface area of 30 mm2 to 2 mm2 and a length of 2 mm to 25 mm and wherein the microparticles of a hydrophilic polymeric gel has a pore radius of 3 to 60 μm.