Testosterone Transdermal Formulation for Absorption Without Exudation
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Solution Overview
Problem
Existing transdermal formulations for testosterone suffer from low drug releasability and formulation properties due to the use of pressure-sensitive adhesives and oily solvents, leading to exudation and adverse skin reactions.
Innovation Solution
A transdermal formulation containing polyacrylic acid or its salt, a thickener, a cross-linking agent, propylene glycol as a plasticizer, and a lactic acid ester as the main base, which enhances skin permeability and maintains formulation integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pressure sensitive adhesives such as acrylic adhesives are used as the base in transdermal formulations, then the formulation can be applied easily to the skin, but the drug releasability is low and a large amount of solubilizers and absorption enhancers are needed, worsening formulation properties
Solution Approach 1:
The patent changes the chemical composition parameters of the base from conventional pressure-sensitive adhesives to a specific combination of water-soluble polymer, oily solvent, and surfactant in controlled ratios. This parameter change enables the base itself to provide drug releasability without requiring excessive solubilizers and absorption enhancers, thus resolving the contradiction between ease of application and formulation quality.
Solution Approach 2:
The patent creates a composite base material combining water-soluble polymers (for adhesion), oily solvents (for drug solubility), and surfactants (for drug releasability). This composite structure integrates multiple functions into a single base system, eliminating the need for separate large amounts of solubilizers and absorption enhancers while maintaining ease of application.
2Quantity of substance
If nonaqueous bases containing water-soluble polymers are used, then hydrophilic solvents can be contained in relatively large amounts, but oily absorption enhancers separate from the formulation and exude, causing decreased adhesive force
Solution Approach 1:
The patent introduces surfactants as intermediary substances that mediate between the hydrophilic water-soluble polymer base and the hydrophobic oily absorption enhancers. The surfactants form micellar structures that solubilize the oily components within the water-based matrix, preventing phase separation and exudation while maintaining formulation stability and adhesive properties.
Solution Approach 2:
The patent carefully controls the ratio parameters between water-soluble polymer, oily solvent, and surfactant components. By optimizing these compositional parameters, the formulation achieves a stable microemulsion-like structure where oily absorption enhancers remain dispersed within the hydrophilic base without separating or exuding during storage.
3Productivity
If lactic acid ester is contained as an absorption enhancer, then transdermal absorbability is enhanced, but the lactic acid ester exudes from the formulation during storage, causing liquid ingredients to adhere to release liners and decreasing formulation properties
Solution Approach 1:
The patent uses surfactants as intermediary agents that interact with the lactic acid ester absorption enhancer. The surfactants form stable micellar complexes with the lactic acid ester, preventing its exudation from the formulation during storage. This allows the lactic acid ester to remain trapped within the surfactant micelles, maintaining both transdermal absorbability and formulation stability.
Solution Approach 2:
The patent optimizes the concentration ratio between lactic acid ester and surfactant, and adjusts the HLB value parameters of the surfactant selection. By controlling these parameters, the formulation achieves a critical micelle concentration that effectively encapsulates the lactic acid ester, preventing exudation while maintaining its transdermal penetration enhancement function.
4Stability of the object's composition
If surfactants are contained to suppress exudation of oily solvents, then formulation properties are maintained, but cutaneous irritation occurs
Solution Approach 1:
The patent carefully controls the concentration parameter of surfactants within a narrow optimal range and selects surfactants with specific HLB values that balance emulsification capability with skin compatibility. By optimizing these parameters, the formulation achieves sufficient surfactant levels to prevent oily solvent exudation while maintaining skin tolerance and avoiding cutaneous irritation.
Solution Approach 2:
The patent uses different types of surfactants (anionic, cationic, nonionic) with different local properties in combination, where each surfactant type contributes differently to the overall formulation stability and skin compatibility. This localized functional differentiation allows the formulation to achieve exudation suppression while minimizing irritant effects through synergistic interactions among different surfactant components.
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 provides excellent transdermal absorbability and formulation properties, preventing or treating conditions associated with testosterone deficiency without exudation or skin irritation.
Implementation Method 1
a cross-linking agent
Implementation Method 2
polyacrylic acid or a salt thereof... in a pasty preparation
Implementation Method 3
propylene glycol as a plasticizer
Implementation Method 4
lactic acid ester as an absorption enhancer... excellent skin permeability of testosterone
Data Source
AI summary
The present invention provides a testosterone-containing transdermal formulation having excellent skin permeability of testosterone and excellent formulation properties. Specifically, the present invention provides a transdermal formulation comprising testosterone; polyacrylic acid or a salt thereof; a thickener; a cross-linking agent; a plasticizer comprising propylene glycol; and a lactic acid ester in a pasty preparation.