Donepezil Transdermal Patch Using SIS Adhesive and Solubilizer
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Solution Overview
Problem
Current percutaneous absorption preparations for treating dementia with donepezil suffer from low skin penetration, skin irritation, and physicochemical instability due to crystal precipitation, making them ineffective for elderly patients.
Innovation Solution
A percutaneous absorption preparation comprising donepezil, propylene glycol monocaprylate as a solubilizer, and styrene-isoprene-styrene block copolymer as an adhesive, which enhances skin penetration without crystal precipitation and irritation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the drug level or penetration enhancers is increased to improve skin penetration, then the degree of skin penetration is improved, but crystal precipitation and skin irritation occur
Solution Approach 1:
The patent changes the chemical parameters of the penetration enhancer by selecting specific compounds (oleic acid, isopropyl myristate, or propylene glycol monocaprylate) within optimized concentration ranges (1-20%, 5-15%, or 3-10% respectively). This parameter optimization enables effective skin penetration while preventing crystal precipitation and skin irritation that occur with higher concentrations or different compounds.
Solution Approach 2:
The patent uses composite adhesive formulations combining specific base polymers (polyisobutylene, polyethylene vinyl acetate copolymer, or styrene-isoprene-styrene block copolymer) with the selected penetration enhancers. This composite approach creates a synergistic system where the adhesive matrix stabilizes the donepezil while the penetration enhancer facilitates skin absorption, achieving both high penetration and stability without irritation.
2Speed
If the drug level or penetration enhancers is increased to improve skin penetration, then the degree of skin penetration is improved, but crystal precipitation occurs
Solution Approach 1:
The patent optimizes the concentration parameters of penetration enhancers to specific ranges (oleic acid 1-20%, isopropyl myristate 5-15%, or propylene glycol monocaprylate 3-10%) that maintain donepezil in solution without precipitation. This parameter control prevents crystal formation while enabling sufficient skin penetration, resolving the contradiction between penetration rate and compositional stability.
Solution Approach 2:
The patent introduces penetration enhancers as intermediary substances that mediate between the donepezil drug and the skin barrier. These intermediaries (oleic acid, isopropyl myristate, or propylene glycol monocaprylate) facilitate drug absorption through their amphiphilic properties, allowing donepezil to penetrate skin effectively without requiring high drug concentrations that would cause precipitation.
3Quantity of substance
If the size of the percutaneous absorption preparation is increased to deliver sufficient drug, then the drug delivery amount is improved, but the device complexity and patient compliance worsen
Solution Approach 1:
The patent changes the formulation parameters by incorporating penetration enhancers that increase the skin permeability coefficient of donepezil. This parameter change allows sufficient drug delivery (26 µg/cm²/hr) through a compact, patient-friendly patch size, eliminating the need for large preparation sizes while maintaining effective dosing.
4Reliability
If oral preparation is used to treat dementia, then the drug delivery effectiveness is improved, but severe side effects and administration convenience problems occur
Solution Approach 1:
The patent replaces the oral administration route with a transdermal delivery system. This substitution eliminates the gastrointestinal tract as the delivery pathway, avoiding nausea, vomiting, and diarrhea side effects while providing continuous, controlled drug release directly through the skin into systemic circulation, maintaining treatment effectiveness without oral administration problems.
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 high skin penetration and stability, providing an effective alternative to traditional oral preparations for treating dementia with minimal side effects.
Implementation Method 1
propylene glycol monocaprylate as a solubilizer
Implementation Method 2
percutaneous absorption preparation for treating dementia comprising donepezil with an excellent degree of skin penetration
Implementation Method 3
styrene-isoprene-styrene block copolymer as an adhesive
Data Source
AI summary
A percutaneous absorption preparation is disclosed. The percutaneous absorption preparation contains donepezil for treatment of dementia, wherein the preparation includes: (a) donepezil or its pharmaceutically acceptable salt as active component, (b) propylene glycol monocaprylate as solubilizer, and (c) styrene-isoprene-styrene block copolymer (“SIS”) as adhesive. The percutaneous absorption preparation has low skin irritation and high skin penetration.