Transdermal Donepezil Free Base Formulation for Reduced Skin Irritation
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Solution Overview
Problem
Conventional transdermally absorbable donepezil-containing preparations often cause skin irritation such as pruritus, flushing, rash, pain, eczema, and dermatitis, while reducing donepezil content to minimize irritation compromises skin permeability rates necessary for treatment.
Innovation Solution
A transdermal preparation combining donepezil with cholesterol compounds, such as cholesterol derivatives and analogs, as skin irritation-reducing agents, to enhance skin permeability while minimizing irritation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the content of donepezil in transdermal preparation is decreased to reduce skin irritation, then skin irritation is reduced, but skin permeability rate necessary for treatment cannot be ensured
Solution Approach 1:
The patent changes the chemical form of donepezil from hydrochloride salt to free base form, and controls the pH of the preparation to be between 3-7. This parameter change allows the donepezil to maintain higher skin permeability while reducing skin irritation, as the free base form is more lipophilic and can penetrate skin more effectively without causing severe irritation.
Solution Approach 2:
The patent creates a composite transdermal preparation system combining donepezil free base with specific excipients including pH buffers, transdermal absorption enhancers, and adhesion promoters. This composite formulation achieves both reduced skin irritation and sufficient skin permeability through synergistic interactions among components.
2Quantity of substance
If conventional transdermal preparation formulations are used, then skin permeability can be achieved, but skin irritation such as pruritus, flushing, rash, pain, eczema and dermatitis occurs
Solution Approach 1:
The patent adjusts the pH parameter of the preparation to be between 3-7, which is closer to physiological pH, thereby reducing skin irritation. Additionally, converting donepezil hydrochloride to donepezil free base changes the chemical form to be less irritating while maintaining or improving skin permeability.
Solution Approach 2:
The patent introduces transdermal absorption enhancers and pH buffers as intermediary substances that facilitate donepezil penetration into the skin while simultaneously reducing direct contact irritation. These intermediaries mediate between the drug and skin tissue to achieve both permeability and comfort.
3Quantity of substance
If donepezil hydrochloride is used in transdermal preparation, then sufficient skin permeability can be achieved, but severe skin irritation occurs
Solution Approach 1:
The patent fundamentally changes the chemical parameter of donepezil from hydrochloride salt form to free base form. This parameter change reduces the ionic character and hygroscopy of the compound, resulting in reduced skin irritation while the free base form's increased lipophilicity enhances skin permeability.
Solution Approach 2:
The patent replaces the conventional hydrochloride salt formulation approach with a free base formulation approach. This substitution of the chemical system allows for better skin compatibility and permeability characteristics that cannot be achieved with the hydrochloride form alone.
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 use of cholesterol compounds in the transdermal preparation achieves a sufficient skin permeability rate for donepezil while significantly reducing skin irritation, as demonstrated by reduced production of skin irritation mediators and lower primary irritation indices.
Implementation Method 1
it has been well known that steroids with steroidal backbone generally have anti-inflammatory effects
Implementation Method 2
since skin does not generally allow drugs to penetrate, it is difficult to allow a therapeutically effective amount of drug absorbed from the skin into the body
Data Source
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AI summary
Provided is a transdermal preparation having low skin irritation as well as a sufficient skin permeability rate of donepezil, which comprises one or more drugs selected from donepezil and pharmaceutically acceptable salts thereof. Also provided are a manufacturing method thereof, and a method for reducing skin irritation of a transdermally absorbable donepezil-containing preparation. An embodiment is a transdermal preparation comprising one or more drugs selected from donepezil and pharmaceutically acceptable salts thereof, and a skin irritation-reducing agent.