Non-aqueous Lidocaine Patch Dissolving Agent
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Solution Overview
Problem
Existing non-aqueous lidocaine patches face challenges with poor skin permeability and stability due to undissolved lidocaine, leading to inadequate pain relief and potential side effects from high concentrations, while aqueous patches have adhesion issues and require moisture for lidocaine dissolution.
Innovation Solution
A non-aqueous patch using a dissolving agent composed of an organic acid and polyalcohol to completely dissolve 0.5 to 7% lidocaine, ensuring stable release over 12 hours, with a low plaster mass and flexible elastomer base for improved adhesion and skin penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lidocaine is used in high concentration (5-100 wt.%) in non-aqueous patches, then the pain-relieving effect is improved, but side effects increase and the drug requires prescription
Solution Approach 1:
The patent optimizes the lidocaine concentration parameter to a specific range (0.5-5 mass %) that balances therapeutic effectiveness with safety, allowing household use without prescription while maintaining adequate pain relief. This parameter optimization resolves the contradiction by finding the optimal concentration point that satisfies both efficacy and safety requirements.
2Object-affected harmful factors
If lidocaine is used in small amount (0.5-5 mass %) for household use, then side effects are reduced, but the lidocaine cannot be stably released over long period and cannot permeate into skin
Solution Approach 1:
The patent employs a composite plaster composition containing multiple components including organic acids (salicylic acid, benzoic acid), polyols (glycerin, propylene glycol), and elastomers in specific proportions. This composite material system enables stable release of small amounts of lidocaine over extended periods (12+ hours) and facilitates skin permeation, resolving the contradiction between low concentration safety and long-term release stability.
Solution Approach 2:
The patent introduces organic acids and polyols as intermediary substances that facilitate the release and permeation of lidocaine. These intermediaries act as carriers and promoters that enable efficient delivery of low concentrations of lidocaine through the skin over extended periods, solving the problem of unstable release and poor permeation at low drug concentrations.
3Stability of the object's composition
If aqueous base patch is used, then lidocaine can be dissolved, but the patch has thick plaster, poor skin compatibility, and adhesion problems
Solution Approach 1:
The patent transitions from aqueous base to non-aqueous plaster base, changing the fundamental composition parameter. The plaster contains 20-40 mass % elastomer and specific ratios of organic acids and polyols, creating a non-aqueous system that dissolves lidocaine effectively while providing thin plaster structure, good skin compatibility, and reliable adhesion for prolonged wear.
4Stability of the object's composition
If non-aqueous patch with undissolved lidocaine is used, then the plaster structure is maintained, but skin permeability is poor
Solution Approach 1:
The patent changes the physical state parameter of lidocaine from crystalline/undissolved to completely dissolved by selecting appropriate solvents (organic acids and polyols) and optimizing concentration and composition parameters. This dissolution transformation maintains plaster structural integrity while dramatically improving skin permeability, allowing efficient drug delivery through the skin.
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 patch achieves efficient and stable lidocaine release for prolonged pain relief with reduced side effects and improved adhesion, maintaining skin permeability and safety for household use.
Implementation Method 1
a dissolving agent composed of an organic acid and a polyalcohol was used, and 0.5 to 7 mass % of lidocaine and/or its reactant was mixed in a plaster, thereby producing a non-aqueous patch in which the lidocaine is completely dissolved
Implementation Method 2
the small amount of lidocaine is percutaneously absorbed stably over a long period of time and permeates into the muscle
Implementation Method 3
lidocaine can be used as a non-aqueous patch that can relieve muscular pain over a long period of time
Data Source
AI summary
Non-aqueous patches comprising lidocaine, which is not dissolved and is present in a crystalline state, have poor permeability to the skin. Therefore, non-aqueous patches have a high concentration of lidocaine. It is pointed out that lidocaine has an adverse effect on the heart. Prolonged use of a high concentration of lidocaine causes side effects, such as shock, rubor, and irritating sensation. External preparations comprising more than 5 mass % of lidocaine are designated as powerful drugs, and cannot be used as household (nonprescription) medicine. Provided is a non-aqueous patch that is effective to relieve muscle pain, the non-aqueous patch comprising lidocaine and/or its reactant, and a dissolving agent composed of an organic acid and a polyalcohol, which are contained in a base.