Adhesive Sheet with Diblock Copolymer Mixture for Low Irritation
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Solution Overview
Problem
Transdermal absorption preparations using rubber adhesive bases face issues with drug releaseability and skin irritation due to the use of tackifiers, and existing formulations with thermoplastic elastomers and liquid paraffin can be inconsistent in adhesive properties.
Innovation Solution
An adhesive sheet with a mixture of triblock and diblock copolymers, where the diblock copolymer content is at least 20 wt%, and a non-volatile hydrocarbon oil in excess of 50 parts by weight per 100 parts of elastomer, providing sufficient adhesive properties and low skin irritation without the need for tackifiers, and incorporating a drug or its pharmaceutically acceptable salt for improved drug releaseability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rubber adhesive base is used for transdermal absorption preparation, then adhesiveness is improved, but drug releaseability deteriorates and skin irritation increases due to tackifiers
Solution Approach 1:
The invention changes the chemical composition parameters of the adhesive base by using a specific thermoplastic elastomer (mixture of triblock and diblock copolymers with diblock content ≥20 wt%) and a large amount of non-volatile hydrocarbon oil (50-800 parts by weight per 100 parts of elastomer). This parameter change resolves the contradiction by achieving sufficient adhesiveness through the elastomer-oil system while eliminating tackifiers that hinder drug releaseability.
Solution Approach 2:
The invention creates a composite adhesive base system combining thermoplastic elastomer (specific block copolymer mixture) with non-volatile hydrocarbon oil. This composite material approach allows the elastomer to provide adhesive strength while the hydrocarbon oil facilitates drug release, resolving the contradiction between adhesiveness and drug releaseability without requiring tackifiers.
2Strength
If a rubber adhesive base with tackifier is used, then adhesiveness is improved, but skin irritation increases
Solution Approach 1:
The invention extracts and eliminates the tackifier component from the adhesive base formulation. By using the thermoplastic elastomer (triblock+diblock copolymer mixture) combined with non-volatile hydrocarbon oil, the system achieves sufficient adhesiveness without the harmful tackifier, thereby reducing skin irritation while maintaining adhesive strength.
Solution Approach 2:
The invention changes the adhesive base composition by substituting the tackifier-containing rubber adhesive with a tackifier-free thermoplastic elastomer system. This parameter change in chemical composition eliminates the source of skin irritation while maintaining adhesiveness through the elastomer-hydrocarbon oil interaction.
3Object-affected harmful factors
If thermoplastic elastomer and liquid paraffin are used in existing formulations, then skin irritation is reduced, but adhesive property becomes insufficient and inconsistent
Solution Approach 1:
The invention optimizes the parameters of the thermoplastic elastomer system by specifying a minimum diblock copolymer content (≥20 wt%) in the triblock+diblock mixture and defining a specific range for non-volatile hydrocarbon oil content (50-800 parts by weight per 100 parts of elastomer). These parameter changes ensure consistent and sufficient adhesive properties while maintaining low skin irritation, resolving the inconsistency of existing formulations.
Solution Approach 2:
The invention creates a optimized composite material system using specific ratios of thermoplastic elastomer (with controlled diblock content) and non-volatile hydrocarbon oil. This composite approach ensures consistent adhesive performance by balancing the elastomer's adhesive strength with the hydrocarbon oil's plasticizing and skin-compatibility effects, overcoming the inconsistency of previous formulations.
Data Source
AI summary
Provided is an adhesive sheet for adhesion to the skin, which has sufficient adhesiveness and causes low skin irritation. Moreover, provided is a transdermal absorption preparation having, in addition to the above-mentioned property, sufficient drug releaseability. An adhesive sheet for adhesion to the skin, which comprises a support and an adhesive layer formed on the support, wherein the adhesive layer contains at least a thermoplastic elastomer, and a non-volatile hydrocarbon oil in an amount exceeding 50 parts by weight and not more than 800 parts by weight per 100 parts by weight of the elastomer, and the thermoplastic elastomer is a mixture of a triblock copolymer and a diblock copolymer, wherein the content of the diblock copolymer in the mixture is not less than 20 wt%.