Ropinirole Adhesive Patch Using Weak-Base Salts for Skin Permeation

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Solution Overview

Problem

Existing methods for improving the skin permeability of ropinirole and its pharmaceutically acceptable salts in transdermal patches are inadequate, despite the use of absorption enhancers and desalting agents like sodium hydroxide.

Innovation Solution

Incorporating specific sodium carboxylates, such as sodium pentanoate, disodium glutarate, and sodium hexanoate, into the adhesive agent layer of a ropinirole-containing patch, along with a backing layer, to enhance skin permeability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If strong desalting agents such as sodium hydroxide are used to improve skin permeability of ropinirole, then skin permeability is enhanced, but cohesion and growth of metal salt occur over time

Engineering Contradiction:
Improveskin permeabilityVSAvoidcohesion and growth of metal salt
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical parameters by replacing strong desalting agents (sodium hydroxide) with weak base salts (sodium carboxylates with pKa 4-6). This parameter change maintains the desalting function while eliminating the harmful effects of strong bases, thereby improving both skin permeability and long-term stability without metal salt cohesion

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses weak base salts that are consumed during the desalting process without causing long-term stability issues. These salts perform their function of converting acid addition salts to free base form for transdermal absorption and then remain stable in the adhesive layer without causing metal salt cohesion or growth over time

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Reliability

If absorption enhancers are used to improve transdermal absorption of ropinirole, then skin permeability is enhanced, but device complexity increases

Engineering Contradiction:
Improvetransdermal absorptionVSAvoidconfiguration complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the desalting function and absorption enhancement function into a single component - weak base salts (sodium carboxylates). This merging eliminates the need for separate absorption enhancer systems while maintaining effective transdermal absorption of ropinirole, thereby reducing device complexity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The weak base salts serve multiple functions: they act as desalting agents to convert acid addition salts to free base form, provide absorption enhancement for transdermal delivery, and maintain long-term stability in the adhesive layer. This multi-functionality reduces the overall complexity of the transdermal patch system

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 improved skin permeability of ropinirole and its salts, maintaining cohesive force and adhesiveness, even without the use of strong desalting agents.

Implementation Method 1

it is also known to cause free ropinirole (free form) to be transdermally absorbed by desalting an acid addition salt of ropinirole with a desalting agent during production of the preparation or in the produced preparation

Methodology Applied
Scientific EffectChemical reaction (desalting): Chemical Bonding

Implementation Method 2

excellent skin permeability is required. PTLs 1 to 6 state that absorption enhancers for enhancing transdermal absorption of ropinirole and/or a pharmaceutically acceptable salt thereof may be used

Methodology Applied
Scientific EffectTransdermal permeation: Permeation

Data Source

PatentEP4238563B1Ropinirole-containing patch and method for improving skin permeability of ropinirole
Publication Date: 2025.09.24 HISAMITSU PHARM CO INC

AI summary

A ropinirole-containing patch comprising a backing layer and an adhesive agent layer, wherein the adhesive agent layer comprising: at least one selected from the group consisting of ropinirole and a pharmaceutically acceptable salt thereof; at least one sodium carboxylate selected from the group consisting of sodium pentanoate, disodium glutarate, and sodium hexanoate; and an adhesive agent.