Trometamol Stabilization of Thermally Unstable Eye Drops

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Solution Overview

Problem

Thermally unstable medicaments in eye drops, such as tafluprost and isopropropyl unoprostone, degrade when storage temperatures rise, leading to reduced drug efficacy and potential turbidity or suspended matter, and existing methods do not effectively prevent this degradation outside of cold storage.

Innovation Solution

Adding trometamol to the eye drop, adjusting the pH to a range of 4 to 8, effectively stabilizes tafluprost or isopropyl unoprostone by preventing thermal hydrolysis of the ester bond, using a water-soluble organic amine with a hydroxy group.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the storage temperature is increased during distribution or storage, then the ease of operation is improved, but the stability of the medicament composition deteriorates due to thermal degradation

Engineering Contradiction:
Improvestorage convenienceVSAvoidmedicament stability
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

Trometamol acts as an intermediary substance that mediates between the thermally unstable medicament and the thermal environment. It forms a protective interaction with the medicament (particularly with ester bonds) to prevent thermal hydrolysis and degradation, allowing the eye drop to be stored at higher temperatures without compromising medicament stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical environment parameters of the eye drop formulation by introducing trometamol, which alters the pH and chemical reactivity parameters. This creates a more stable chemical environment that resists thermal degradation, enabling storage at temperatures above refrigeration conditions while maintaining medicament integrity.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If cold storage is used to prevent medicament degradation, then the stability of the medicament composition is improved, but the ease of operation deteriorates due to storage restrictions

Engineering Contradiction:
Improvemedicament stabilityVSAvoidstorage convenience
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The invention replaces the need for expensive and restrictive cold chain storage infrastructure with a simple chemical stabilizer (trometamol) that can be incorporated into the formulation itself. This eliminates the need for continuous refrigeration, making the product accessible in settings without cold storage capabilities.

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

Solution Approach 2:

The eye drop formulation becomes self-stabilizing through the inclusion of trometamol, which provides intrinsic protection against thermal degradation. The formulation protects itself without requiring external cold storage conditions, enabling autonomous stability maintenance across various storage environments.

Inventive Principle:
Principle #25Self-service

3Ease of operation

If water-soluble organic amine is added as a buffer, then the ease of operation is improved, but the stability of the medicament composition may deteriorate due to unwanted side effects

Engineering Contradiction:
Improveformulation flexibilityVSAvoidmedicament stability
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The invention applies the buffering function locally to where it is most needed - in the immediate chemical environment of the thermally unstable medicament. Trometamol is positioned to specifically protect the medicament from thermal hydrolysis through localized chemical interaction, rather than providing general bulk buffering.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention optimizes the pH parameter within a specific range (4-8) to achieve maximum stabilizing effect while minimizing unwanted side effects. This parameter optimization ensures that the organic amine provides thermal protection without causing precipitation, turbidity, or other adverse reactions.

Inventive Principle:
Principle #35Parameter changes

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 method significantly reduces the degradation of tafluprost or isopropyl unoprostone, as demonstrated by a heat stability test showing higher residual ratios compared to traditional buffer systems, ensuring a stable eye drop composition even at elevated temperatures.

Implementation Method 1

the thermally unstable medicament has an ester bond and a tendency to be thermally hydrolyzed

Methodology Applied
Scientific EffectThermal hydrolysis: Hydrolysis

Implementation Method 2

adjusting the pH of the eye drop in the range of from 4 to 8

Methodology Applied
Scientific EffectpH adjustment:

Data Source

PatentEP1916002B1Method for prevention of degradation of thermally unstable substance
Publication Date: 2014.03.05 SANTEN PHARMACEUTICAL CO LTD

AI summary

The present invention provides a method for preventing the degradation of a thermally unstable medicament in an eye drop containing the medicament thereby to stabilize the eye drop. By adding an organic amine to an eye drop containing a thermally unstable medicament, the degradation of the medicament in the eye drop can be effectively prevented, and therefore the eye drop can be stably stored.