Diclofenac Emulsified Gel Stability via Nonionic Polymer
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Solution Overview
Problem
Diclofenac sodium exhibits low stability in emulsified gel compositions, leading to decomposition products formation during storage, which affects the efficacy and shelf life of transdermal formulations.
Innovation Solution
An emulsified gel composition comprising diclofenac sodium, water, a nonionic water-soluble polymer gelling agent like hydrophobically-modified hydroxypropyl methyl cellulose, an antioxidant, and a surfactant with an HLB of 14 or more, with minimal ionic polymer content, which enhances stability and skin application feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an emulsified gel composition is formulated with diclofenac sodium, then use feeling at the time of and after application onto the skin is improved, but drug stability of diclofenac sodium deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by selecting specific nonionic water-soluble polymers (hydroxypropyl cellulose or hydrophobically-modified hydroxypropyl methyl cellulose) as gelling agents and specifying surfactants with HLB values of 14 or more. This parameter optimization resolves the contradiction by creating an emulsified gel system that simultaneously provides excellent use feeling and maintains diclofenac sodium stability above 98% after 1 month at 60°C storage.
2Strength
If ionic polymer is added to emulsified gel composition, then gel structure is enhanced, but drug stability decreases
Solution Approach 1:
The patent extracts or removes ionic polymers from the formulation entirely, or limits them to 0.5% by mass or less based on the mass of the whole emulsified gel composition. This elimination of the harmful component (ionic polymer) resolves the contradiction by preventing drug stability deterioration while maintaining adequate gel structure through alternative nonionic polymer systems.
Solution Approach 2:
The patent introduces nonionic water-soluble polymers as intermediary substances that can provide the necessary gel structure and stability without causing drug decomposition. These nonionic polymers act as mediators that fulfill the structural requirement while being compatible with diclofenac sodium stability, unlike ionic polymers.
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 maintains 98% or more diclofenac sodium stability after 1 month at 60°C, improving drug stability and skin application characteristics, such as reduced stickiness and improved spreadability.
Implementation Method 1
a gelling agent, and wherein the gelling agent is a nonionic water-soluble polymer selected from the group consisting of hydroxypropyl cellulose and hydrophobically-modified hydroxypropyl methyl cellulose
Implementation Method 2
hydrophobically-modified hydroxypropyl methyl cellulose
Implementation Method 3
a surfactant having an HLB of 14 or more
Implementation Method 4
an antioxidant
Data Source
Figure 1
AI summary
The present invention provides an emulsified gel composition comprising diclofenac sodium, water, a gelling agent, an antioxidant, and a surfactant having an HLB of 14 or more, in which the gelling agent is a nonionic water-soluble polymer.