Topical Gel Composition Preventing Methylparaben Crystallization
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Solution Overview
Problem
Topical gel compositions containing carbomer and methylparaben often develop crystalline particles, which compromise their antimicrobial effectiveness over extended storage periods, particularly when methylparaben concentrations exceed 0.15% w/w.
Innovation Solution
Formulating topical gels with 0.05 to 0.20% w/w methylparaben, 0.80 to 1.50% w/w carbomer, and 9.0 to 13.0% w/w total polyol, maintaining a pH of 4.5 to 7.5, and ensuring the carbomer concentration is less than 1.25% w/w when methylparaben exceeds 0.15% w/w, along with the inclusion of additional preservatives like phenoxyethanol, to prevent crystallization and maintain microbiological quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If methylparaben concentration is increased to enhance antimicrobial effectiveness, then preservative efficacy is improved, but crystalline particles form compromising product quality
Solution Approach 1:
The patent applies parameter changes by adjusting the pH of the formulation to a specific range (4.5-7.5) and controlling the concentration ratio between methylparaben and carbomer. This resolves the contradiction by maintaining methylparaben at effective concentrations (0.05-0.20%) while preventing crystallization through pH control and synergistic interaction with carbomer.
Solution Approach 2:
The patent uses carbomer as an intermediary substance that mediates between methylparaben and the aqueous environment. The carbomer (at 0.80-1.50% concentration) acts as a stabilizing agent that prevents methylparaben crystallization while allowing it to maintain effective antimicrobial levels, thus resolving the contradiction between efficacy and stability.
2Reliability
If methylparaben concentration exceeds 0.15% w/w to ensure preservative efficacy, then antimicrobial protection is enhanced, but crystalline particle formation increases
Solution Approach 1:
The patent applies parameter changes by establishing a conditional relationship between methylparaben and carbomer concentrations. When methylparaben exceeds 0.15%, the carbomer concentration is controlled to be less than 1.25%, and the pH is maintained within 4.5-7.5. This resolves the contradiction by preventing crystallization through controlled parameter interactions while maintaining effective preservative levels.
3Duration of action of stationary object
If extended storage period is required to meet stability requirements, then shelf life is improved, but antimicrobial effectiveness deteriorates due to preservative degradation
Solution Approach 1:
The patent applies preliminary action by incorporating carbomer into the formulation before methylparaben, creating a stabilized matrix that prevents preservative degradation during storage. The carbomer is included at 0.80-1.50% concentration to establish a protective environment that maintains methylparaben solubility and effectiveness throughout the extended shelf life.
Solution Approach 2:
The patent uses carbomer as an intermediary that protects methylparaben from degradation during extended storage. The carbomer-methylparaben interaction system maintains preservative efficacy over time by preventing crystallization and degradation, thus resolving the contradiction between extended shelf life and maintained effectiveness.
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 formulation effectively prevents the formation of methylparaben crystalline particles, ensuring the gel's antimicrobial efficacy is sustained over an extended period, meeting both USP and EP preservative-efficacy testing criteria.
Implementation Method 1
crystalline particles of methylparaben have been unexpectedly observed in some brimonidine topical gel formulations and placebo formulations containing carbomer and methylparaben
Implementation Method 2
the formulation effectively prevents the formation of methylparaben crystalline particles
Data Source
AI summary
Improved topical gel compositions for the treatment of skin disorders are described. The gel compositions contain carbomer and methylparaben, and are substantially free of methylparaben crystalline particles after an extended period of storage.