Borate-Phosphate Buffer Compositions for Ophthalmic Devices
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Solution Overview
Problem
Formulating ophthalmic packaging solutions that maintain physiological pH, are bacteriostatic, and compatible with contact lenses while avoiding eye irritation and microbial growth promotion, is challenging due to the limitations of boric acid/borate and phosphate buffers.
Innovation Solution
Combining boric acid/borate with phosphates at specific ratios to create bacteriostatic compositions that maintain physiological pH and are compatible with contact lenses, using concentrations of 0.1-0.8% w/v borate and 0.3-0.9% w/v phosphate, with the phosphate concentration being at least 1.5 times that of borate, in an ophthalmologically acceptable carrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If boric acid/borate is used as buffer at low concentrations to maintain pH near physiological pH, then eye irritation is reduced, but bacteriostatic efficacy against certain microorganisms (e.g., Pseudomonas aeruginosa) is sacrificed
Solution Approach 1:
The patent combines boric acid/borate buffer with phosphate buffer in a specific formulation to achieve both bacteriostatic efficacy and low eye irritation. The boric acid/borate component provides pH buffering near physiological pH with reduced eye irritation, while the phosphate component enhances the bacteriostatic effect against microorganisms like Pseudomonas aeruginosa, thereby merging the benefits of both buffer systems to resolve the contradiction between comfort and efficacy.
2Stability of the object's composition
If phosphates are used as buffer to maintain pH, then buffering capacity is achieved, but microbial growth is promoted
Solution Approach 1:
The patent merges phosphate buffer with boric acid/borate buffer in a specific formulation. The phosphate component provides robust pH buffering capacity, while the boric acid/borate component counteracts the microbial growth promotion effect of phosphates by providing additional bacteriostatic activity. This combination allows the formulation to maintain both stable pH and effective microbial growth control.
3Reliability
If packaging solution is formulated to be bacteriostatic, then microbial growth is inhibited, but eye comfort and compatibility with contact lens materials may be compromised
Solution Approach 1:
The patent combines boric acid/borate and phosphate buffers in specific concentrations to achieve bacteriostatic properties while maintaining eye comfort. The boric acid/borate component provides pH buffering near physiological pH which is gentle to the eye, while the phosphate component enhances bacteriostatic efficacy. This merged formulation achieves both goals simultaneously rather than sacrificing one for the other.
Solution Approach 2:
The patent optimizes the concentrations of boric acid/borate and phosphate components to specific ranges that simultaneously provide bacteriostatic efficacy and eye comfort. By carefully adjusting these parameters (concentrations, ratios), the formulation achieves the desired balance between microbial inhibition and ocular compatibility.
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 compositions effectively inhibit microbial growth, maintaining eye comfort and compatibility with contact lenses, as demonstrated by reduced microbial colony forming units and pH stability, providing a safe and effective packaging solution.
Implementation Method 1
An important component of ophthalmic compositions, including packaging solutions, is the buffer incorporated, which helps to maintain the pH of the composition within an acceptable physiological range
Implementation Method 2
boric acid/borate as the buffer relates to its unique ability to maintain formulation (to which it is added) pH near physiological pH (∼7) with a secondary impact of imparting at, low concentrations, bacteriostatic (as opposed to bactericidal) characteristics to formulations
Data Source
AI summary
The present invention relates to borate and phosphate containing compositions, especially eye care compositions, achieving physiologically compatible pH and tonicity as well as good bacteriostatic properties. Methods of using the compositions of the present invention are also disclosed.