Non-aqueous Lidocaine Patch Adhesion via Biaxially-Oriented Cloth

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Solution Overview

Problem

Aqueous-based lidocaine patches have poor adhesive properties, leading to easy removal and inadequate lidocaine delivery, while non-aqueous patches with high lidocaine concentrations face issues with skin permeability and side effects, and those with low concentrations struggle with stable long-term release.

Innovation Solution

A non-aqueous patch using a biaxially-oriented stretch cloth support with controlled adhesive power and a composition of polyisoprene rubber, styrene-isoprene-styrene block copolymer, terpene resin, and anhydrous silicic acid to maintain adhesion and ensure effective transdermal absorption of a low concentration of lidocaine.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If aqueous base patches are used for lidocaine delivery, then lidocaine can be dissolved and applied to skin, but the patches have poor adhesion and are difficult to attach for long periods

Engineering Contradiction:

Improvelidocaine delivery amountVSAvoidadhesion stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the base parameter from aqueous to non-aqueous (oil-based), which fundamentally alters the adhesion properties while maintaining lidocaine solubility through appropriate solvent selection

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite plaster composition containing multiple ingredients including oil-based components, resins, and lidocaine to achieve both good adhesion and effective drug delivery

Inventive Principle:

Principle #40Composite materials

2Reliability

If high concentration of lidocaine is used in non-aqueous patches, then adhesion improves, but skin permeability decreases and side effects increase

Engineering Contradiction:

Improveadhesion strengthVSAvoidskin irritation and side effects

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent optimizes the lidocaine concentration parameter to a specific range (0.5-5 mass%) that balances adhesion requirements with safety and permeability considerations

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces oil-based solvents and plasters as intermediaries that facilitate lidocaine permeation through the skin at lower concentrations, reducing the need for high doses

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If low concentration of lidocaine is used in non-aqueous patches, then side effects are reduced, but stable long-term release cannot be achieved

Engineering Contradiction:

Improveside effectsVSAvoidrelease stability

Core Design Contradiction:

Object-affected harmful factorsVSDuration of action of stationary object

Solution Approach 1:

The patent creates a composite plaster system with multiple components (oils, resins, emollients) that work together to enable controlled, sustained release of low-concentration lidocaine over extended periods

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent utilizes the porous structure of the plaster matrix to facilitate gradual lidocaine permeation and sustained release kinetics

Inventive Principle:

Principle #31Porous materials

4Stability of the object's composition

If lidocaine is present in crystalline state in non-aqueous patches, then storage stability improves, but skin permeability decreases

Engineering Contradiction:

Improvestorage stabilityVSAvoidpermeability

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical state parameter of lidocaine from crystalline to dissolved state by selecting appropriate oil-based solvents, thereby enabling skin permeation while maintaining formulation stability

Inventive Principle:

Principle #35Parameter changes

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 long-term adhesion and effective lidocaine release, avoiding skin irritation and side effects, with a release ratio of more than 6% over 12 hours, providing continuous pain relief without high lidocaine concentrations.

Implementation Method 1

a non-aqueous patch using a biaxially-oriented stretch cloth support with controlled adhesive power

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

ensure effective transdermal absorption of a low concentration of lidocaine

Methodology Applied

Scientific EffectPermeation: Permeation

Data Source

PatentUS11793766B2Non-aqueous patch for the relief of pain

Publication Date: 2023.10.24 ITOCHU CHEM FRONTIER CORP

AI summary

[Problem] If lidocaine is composed of non-aqueous patch, the adhesive power of the preparation tends to get lower, as the composition amount of lidocaine is higher. It is popular to solve lidocaine in dissolving agent in order to compose lidocaine in patch and release effective amount into skin. However, if the amount of dissolving agent gets higher, the adhesive power gets extremely lower, so that an long-time attachment is difficult.[Solution]A non-aqueous patch comprising lidocaine and/or its reactant, and a dissolving agent which are contained in a base of plaster, the plaster being hold by a support, of which strength of 50% stretched to longitudinal direction is less than 2000 g/50 mm and of biaxially-oriented stretch cloth.