Non-Aqueous Lidocaine Patch Composition for Stable Skin Permeation
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Solution Overview
Problem
Existing lidocaine patches face issues with poor skin compatibility, weak adhesion, moisture vaporization, high concentrations leading to side effects, and poor skin permeability due to crystalline state, and challenges in maintaining long-term drug release and skin permeation.
Innovation Solution
A non-aqueous topical patch formulation with 1.8% w/w lidocaine, using a combination of high and low molecular weight polyisobutylene, styrene-isoprene-styrene block copolymer, mineral oil, isopropyl myristate, and silicon dioxide, optimized for controlled dermal delivery, with a solvent-based processing method to ensure stability and adhesive performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high concentrations of lidocaine are used in non-aqueous patches, then the analgesic effect is enhanced, but skin permeability deteriorates due to crystalline state formation
Solution Approach 1:
The patent optimizes the concentration of lidocaine to 1.8% w/w and adjusts the ratio of permeation enhancers (isopropyl myristate and oleic acid) to prevent lidocaine crystallization while maintaining effective analgesic delivery. This parameter optimization resolves the contradiction by finding the optimal balance between drug concentration and solubility/permeability.
Solution Approach 2:
The patent uses a composite adhesive matrix combining polyisobutylene, styrene-isoprene-styrene block copolymer, mineral oil, and multiple permeation enhancers (isopropyl myristate and oleic acid). This composite formulation prevents lidocaine crystallization and enhances skin permeability while maintaining effective drug delivery.
2Object-affected harmful factors
If aqueous base patches are used for lidocaine delivery, then skin compatibility is improved, but adhesion strength deteriorates
Solution Approach 1:
The patent transitions from aqueous to non-aqueous base formulation and optimizes the adhesive matrix composition to achieve both skin compatibility and strong adhesion. The specific ratio of polymers and oils in the adhesive layer resolves the contradiction between these two properties.
Solution Approach 2:
The patent employs a composite adhesive system combining polyisobutylene, styrene-isoprene-styrene block copolymer, and mineral oil that provides both skin compatibility and strong adhesion, eliminating the trade-off present in aqueous formulations.
3Strength
If non-aqueous base patches are used for lidocaine delivery, then adhesion strength is improved, but moisture vaporization issues occur
Solution Approach 1:
The patent optimizes the composition of the non-aqueous base by adjusting the ratio of mineral oil and incorporating antioxidants like BHT to control moisture interaction and prevent vaporization, while maintaining strong adhesion properties.
4Stability of the object's composition
If lidocaine is formulated in crystalline state, then formulation stability is improved, but skin permeability deteriorates
Solution Approach 1:
The patent optimizes the concentration of permeation enhancers (isopropyl myristate and oleic acid) to maintain lidocaine in a dissolved state within the adhesive matrix, preventing crystallization while ensuring formulation stability and enhancing skin permeability.
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 achieves sustained analgesic effects for post-herpetic neuralgia with controlled lidocaine release over 6% within 12 hours, minimizing skin irritation and maintaining formulation stability.
Implementation Method 1
the synergistic combination of mineral oil and isopropyl myristate modulates the solubility and thermodynamic activity of lidocaine, facilitating optimal permeation through the skin
Implementation Method 2
a manufacturing method for the non-aqueous lidocaine patch involving solvent-based processing, where ingredients are mixed in an organic solvent such as toluene, followed by coating, drying, and lamination steps
Data Source
AI summary
The present invention relates to a lidocaine non-aqueous topical patch composition comprising approximately 1.8% w/w lidocaine incorporated into a non-aqueous adhesive matrix containing high and low molecular weight polyisobutylenes, hydrogenated polybutene, styrene-isoprene-styrene block copolymer, mineral oil, isopropyl myristate, silicon dioxide, and optionally antioxidants. The formulation provides enhanced skin permeation and sustained drug release with minimal crystallization. The patch is manufactured using a solvent-coating process with toluene, followed by drying and lamination to achieve desired coat weight and adhesive properties. The patch is effective for treating pain conditions such as post-herpetic neuralgia and offers improved stability, ease of application, and reduced risk of irritation.