Preservative-Free Brimonidine Ophthalmic Composition
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Solution Overview
Problem
Conventional ophthalmic compositions containing preservatives like benzalkonium chloride disrupt the tear film's stability and cause ocular irritation, necessitating a preservative-free formulation with optimal surface tension similar to tear fluid to enhance eye comfort and safety.
Innovation Solution
A preservative-free aqueous ophthalmic composition comprising brimonidine 0.025% w/v, combined with tonicity agents such as mannitol and sodium chloride, and surfactants like macrogolglycerol hydroxystearate, polysorbate 20, and polyvinyl alcohol, to achieve a surface tension of 42 mN/m to 46 mN/m, mimicking the natural tear film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If preservatives like benzalkonium chloride are added to eye drops to extend shelf life, then the shelf life is improved, but the tear film stability deteriorates and ocular irritation increases
Solution Approach 1:
The patent removes preservatives from the ophthalmic composition entirely, creating a preservative-free formulation. This extraction of the harmful substance (preservatives) resolves the contradiction by eliminating their destabilizing effect on the tear film while maintaining product safety through alternative packaging or use conditions.
Solution Approach 2:
The patent modifies the formulation parameters by adjusting the composition to be preservative-free, likely changing the concentration of other ingredients or the packaging system to compensate for the lack of preservatives. This parameter change allows the formulation to maintain stability without harmful substances.
2Reliability
If preservatives are added to eye drops to prevent contamination, then the safety against microbial contamination is improved, but the ocular surface irritation worsens
Solution Approach 1:
The patent extracts and removes preservatives from the formulation, eliminating the source of ocular surface irritation. The microbial safety is maintained through alternative means such as single-use packaging or specific storage conditions, resolving the contradiction between safety and irritation.
Solution Approach 2:
The patent may introduce alternative protective mechanisms as intermediaries, such as specific packaging systems or stabilizing agents, that provide microbial protection without the harmful effects of traditional preservatives on the ocular surface.
3Productivity
If conventional ophthalmic formulations are used to deliver drug, then the drug delivery function is achieved, but the tear film stability deteriorates due to preservatives and surfactants
Solution Approach 1:
The patent removes preservatives and potentially modifies surfactant content to eliminate their negative impact on tear film stability. This extraction allows the formulation to maintain drug delivery efficacy while preserving the natural tear film structure.
Solution Approach 2:
The patent changes the formulation parameters by adjusting surfactant concentrations or types, and eliminating preservatives, to achieve a balance between drug delivery effectiveness and tear film stability. The modified parameters enable both functions to coexist.
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 composition provides enhanced comfort and stability to the ocular surface by maintaining optimal tear film properties without the toxic effects associated with preservatives, ensuring uniform drug exposure and prolonged adhesion on the eye.
Implementation Method 1
The surface tension of tear film is found to be between 40 mN/m to 46 mN/m which ensures the optimal tear film stability. Each ophthalmic ingredient including the preservatives, solubilizing agents and thickening agents can influence the surface tension of the final formulation and can solubilize the tear film lipid layer thereby increasing surface tension of tear fluid and reducing tear film stability.
Implementation Method 2
a surfactant selected from the group consisting of macrogolglycerol hydroxystearate, polysorbate 20, polysorbate 80, polyoxyl-40-stearate, propylene glycol, polyethylene glycol (15)-hydroxystearate, 2-[[10,13-dimethyl-17-(6-methylheptan-2-yl)-2,3,4,7,8,9,11,12,14,15,16,17-dodecahydro-1H-cyclopenta[a]phenanthren-3-yl]oxy]ethanol and polyvinyl alcohol
Data Source
AI summary
The present invention relates to preservative-free ophthalmic compositions comprising low-dose of brimonidine.