Fentanyl Transdermal Patch Adhesive Formulation
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Solution Overview
Problem
Conventional fentanyl patches face challenges such as complex manufacturing processes, rapid drug depletion, and poor adhesion due to crystallization, especially in reservoir-type and ion-pair type patches, and lack of skin permeability in polyisobutylene-based patches without mineral oil.
Innovation Solution
A transdermal patch with a pressure-sensitive adhesive layer comprising 75.2-94.2% polyisobutylene, 1-6% fentanyl, and 0.25-0.05 parts mineral oil by mass, using a mixture of high and low molecular weight polyisobutylene and a percutaneous absorption enhancer like isopropyl myristate, which simplifies production and enhances skin permeability and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If reservoir-type patch structure is used to enclose drug solution, then drug stability is improved, but manufacturing complexity increases due to precise preparation steps and drug release controlling membrane
Solution Approach 1:
The invention extracts and eliminates the drug reservoir and drug release controlling membrane from the patch structure. By using a monolithic pressure-sensitive adhesive layer containing fentanyl directly, the complex reservoir-type structure is replaced with a simpler integrated design that maintains drug stability while simplifying manufacturing.
Solution Approach 2:
The invention merges the drug storage function and adhesive function into a single integrated pressure-sensitive adhesive layer. The fentanyl is incorporated directly into the polyisobutylene-based adhesive matrix, eliminating the need for separate reservoir and release membrane components, thus reducing manufacturing complexity while maintaining drug stability.
2Stability of the object's composition
If ion-pair type patch with large amount of organic acid salt is used, then drug stability is improved, but manufacturing complexity increases and drug depletion occurs rapidly
Solution Approach 1:
The invention changes the chemical form of fentanyl from an ion-pair complex requiring large amounts of organic acid salt to a direct incorporation into the polyisobutylene adhesive matrix. This parameter change eliminates the need for complex milling, mixing, and drying conditions while preventing rapid drug depletion through controlled release from the adhesive layer.
3Strength
If polyisobutylene pressure-sensitive adhesive layer with 10-30% fentanyl is used, then adhesion properties are maintained, but fentanyl crystallization occurs over time reducing practical utility
Solution Approach 1:
The invention changes the fentanyl concentration parameter from the conventional 10-30% range to a lower range of 0.1-5% by mass. This parameter change prevents fentanyl crystallization that occurs at higher concentrations over time, while the polyisobutylene-based adhesive matrix maintains adequate adhesion properties. The mineral oil addition further stabilizes the formulation.
4Ease of manufacture
If polyisobutylene adhesive without mineral oil is used, then production cost is reduced, but adhesion to skin and tolerability are poor
Solution Approach 1:
The invention creates a composite pressure-sensitive adhesive material combining polyisobutylene as the base polymer with mineral oil as an additive. This composite structure maintains the cost-effectiveness and ease of manufacture associated with polyisobutylene while the mineral oil component significantly improves adhesion to skin and tolerability, resolving the contradiction between production cost and adhesive performance.
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 long-term fentanyl administration maintaining blood concentration above 1 ng/mL for 48-72 hours with improved adhesion and reduced skin irritation, allowing for easier production and effective pain relief without cohesion failure or adhesive residue.
Implementation Method 1
a transdermal patch for external use, wherein it contains polyisobutylene, a mineral oil and isopropyl myristate as pressure-sensitive adhesive agents and fentanyl
Implementation Method 2
a percutaneous absorption enhancer like isopropyl myristate, which simplifies production and enhances skin permeability
Data Source
AI summary
A transdermal patch for external use having a backing layer and a pressure-sensitive adhesive layer formed on one surface of the backing layer, which contains polyisobutylene, a mineral oil and fentanyl employed as the active ingredient in the pressure-sensitive adhesive layer and in which the contents of polyisobutylene and fentanyl in the pressure-sensitive adhesive layer respectively range from 75.2 to 94.2% by mass and 1 to 6% by mass while the content of the mineral oil is from 0.25 to 0.05 parts by mass based on polyisobutylene. This patch can be easily produced, has a long-lasting effect and is excellent in adhesion to the skin and tolerability against movement to the body parts.