Rivastigmine Transdermal Patch Adhesive Design
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Solution Overview
Problem
Current percutaneous absorption preparations containing rivastigmine cause skin irritation due to interactions between the drug's functional groups and adhesives, leading to reduced skin permeability and increased side effects, and have complex structures that complicate manufacturing.
Innovation Solution
A percutaneous absorption preparation using a styrene-isoprene-styrene block copolymer as the adhesive base, eliminating the need for additional adhesive layers and organic acids, which enhances skin permeability and reduces drug dosage while maintaining adhesion and manufacturing simplicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional adhesives are used in percutaneous absorption preparations containing rivastigmine, then adhesion to skin is achieved, but skin irritation occurs and drug permeation is inhibited due to interactions between rivastigmine's functional groups and the adhesive
Solution Approach 1:
The patent introduces an intermediary substance (oxidized polyisobutylene or oxidized polyethylene) between the rivastigmine and the adhesive. This intermediary layer prevents direct interaction between rivastigmine's functional groups and the adhesive, thereby eliminating skin irritation while maintaining adhesion. The intermediary acts as a barrier that allows the adhesive to function without causing harmful effects.
Solution Approach 2:
The patent changes the chemical parameters of the adhesive system by using oxidized polymers instead of conventional adhesives. This parameter change modifies the chemical compatibility between the adhesive and rivastigmine, reducing harmful interactions while preserving the necessary adhesion properties for skin application.
2Reliability
If conventional adhesives and additional adhesive layers are used to ensure adhesion, then skin adhesion is maintained, but the preparation structure becomes complex and manufacturing difficulty increases
Solution Approach 1:
The patent merges the adhesive function with the polymer matrix by incorporating oxidized polyisobutylene or oxidized polyethylene directly into the preparation formulation. This consolidation eliminates the need for separate adhesive layers, simplifying the overall structure from multiple layers to a integrated single-phase system that maintains adhesion while reducing complexity.
Solution Approach 2:
The oxidized polymer serves multiple functions simultaneously: it acts as both the adhesive component and the matrix material for drug delivery. This multi-functionality eliminates the need for separate adhesive layers, simplifying the preparation structure while maintaining effective skin adhesion.
3Quantity of substance
If higher amounts of rivastigmine are used to ensure sufficient drug delivery, then treatment efficacy is maintained, but skin irritation increases and side effects worsen
Solution Approach 1:
The intermediary (oxidized polymer) enables efficient drug permeation through the skin by preventing adhesive-drug interactions that would otherwise inhibit diffusion. This allows sufficient drug delivery at lower rivastigmine concentrations, reducing skin irritation while maintaining treatment efficacy.
Solution Approach 2:
The patent changes the permeation parameters by using oxidized polymers that enhance drug diffusion through the skin. This parameter change allows achieving sufficient drug delivery at lower rivastigmine doses, thereby reducing skin irritation and side effects while maintaining therapeutic effectiveness.
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 preparation achieves high skin permeability of rivastigmine with reduced side effects and easier manufacturing, delivering a sufficient amount of the drug for dementia treatment using a smaller amount of rivastigmine than conventional patches, with a skin permeation rate greater than 18 µg/cm²/h and a 24-hour cumulative permeation of over 30% of the initial content.
Implementation Method 1
exhibits a high permeability into the skin, carrying a sufficient amount of the drug necessary for treatment of dementia
Implementation Method 2
the functional groups are ready to participate in interactions with an adhesive used in the percutaneous absorption preparation to inhibit diffusion and permeation of rivastigmine into the body through the skin
Data Source
Figure 1~2
AI summary
Disclosed is a percutaneous absorption preparation for treatment of dementia that comprises rivastigmine or its pharmaceutically acceptable salt as an active ingredient, a styrene-isoprene-styrene block copolymer, a tackifier resin, and a plasticizer, which preparation contains a small amount of rivastigmine but allows a sufficient amount of the active ingredient penetrated into the skin to achieve an effective treatment of dementia.