Lyophilized Folate Composition for Oxidation-Stable High Solubility

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Solution Overview

Problem

Existing formulations of 5,10-methylene-(6R)-tetrahydrofolic acid (5,10-CH2-(6R)-THF) suffer from high susceptibility to oxidation and chemical degradation, particularly in aqueous solutions and amorphous forms, limiting their pharmaceutical use due to instability and low active ingredient content.

Innovation Solution

A lyophilized composition comprising the disodium salt of 5,10-methylene-(6R)-tetrahydrofolic acid (5,10-CH2-(6R)-THF*Na2) in combination with citrate and an alkali metal sulfate, without additional reducing agents or antioxidants, achieves high stability and solubility, allowing for a concentration of more than 30% w/w of the active ingredient.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If 5,10-CH2-(6R)-THF is formulated in aqueous solution or amorphous form, then solubility and bioavailability are improved, but chemical stability and resistance to oxidation deteriorate

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

Solution Approach 1:

The patent uses citrate and sulfate as intermediary substances that mediate between the active ingredient and the aqueous environment. These additives form a protective matrix that prevents direct contact between 5,10-CH2-(6R)-THF and oxidizing agents in aqueous solution, thereby maintaining chemical stability while preserving solubility and bioavailability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the pH parameter of the formulation to an alkaline range (pH 7.5-9.0) where 5,10-CH2-(6R)-THF exhibits improved stability. This parameter change, combined with the use of citrate and sulfate, creates an optimal chemical environment that reduces oxidation susceptibility while maintaining adequate solubility for pharmaceutical use.

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If concentration of 5,10-CH2-(6R)-THF is increased to achieve high intracellular levels, then therapeutic effect is improved, but susceptibility to oxidation and degradation increases

Engineering Contradiction:
Improveconcentration of active ingredientVSAvoidresistance to degradation
Core Design Contradiction:
Quantity of substanceVSStability of the object's composition

Solution Approach 1:

Citrate and sulfate act as protective intermediaries that form a stabilizing matrix around the high concentration of 5,10-CH2-(6R)-THF. This matrix prevents oxidative degradation even at elevated concentrations (20-80% w/w), enabling the formulation to achieve both high therapeutic potency and acceptable stability during storage and administration.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite formulation system consisting of 5,10-CH2-(6R)-THF combined with citrate and sulfate in specific ratios. This composite material exhibits synergistic properties where the citrate-sulfate matrix protects the active ingredient from degradation, allowing high concentrations to be maintained without proportionally increasing susceptibility to oxidation.

Inventive Principle:
Principle #40Composite materials

3Stability of the object's composition

If lyophilizate is prepared to improve storage stability, then resistance to oxidation is improved, but complexity of reconstitution and administration increases

Engineering Contradiction:
Improvestorage stabilityVSAvoidease of reconstitution
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The citrate-sulfate system serves as a eutectic mixture that acts as an intermediary between the lyophilized state and reconstituted solution. This intermediary system allows the lyophilizate to be easily reconstituted with simple diluents (water, saline, or buffered solutions) without requiring complex procedures, while maintaining high storage stability in the dried state.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The lyophilization process creates a copied solid-state version of the stable aqueous formulation containing citrate and sulfate. This solid copy preserves the stabilizing effects of the citrate-sulfate system during storage, and upon reconstitution, faithfully reproduces the stable solution characteristics, ensuring consistency between stored and administered formulations.

Inventive Principle:
Principle #26Copying

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 composition maintains high stability and solubility, ensuring effective storage and administration of 5,10-CH2-(6R)-THF*Na2, suitable for cancer treatment, with enhanced storage stability and minimal degradation products.

Implementation Method 1

5,10-CH2-(6R)-THF is highly susceptible to oxidation and chemical degradation that results in unfavorably high impurity levels

Methodology Applied
Scientific EffectOxidation: Oxidation

Implementation Method 2

A lyophilized composition comprising the disodium salt of 5,10-methylene-(6R)-tetrahydrofolic acid

Methodology Applied
Scientific EffectLyophilization: Freeze Drying

Data Source

PatentEP4536187B1Compositions comprising disodium 5,10-methylene-(6R)-tetrahydrofolate
Publication Date: 2026.01.28 MERCK PATENT GMBH
  • EP4536187B1 patent drawingFigure 1
  • EP4536187B1 patent drawingFigure 2
  • EP4536187B1 patent drawingFigure 3

AI summary

The present invention relates to stable formulations and lyophilizates comprising a high content of the disodium salt of 5,10-methylene-(6R)-tetrahydrofolic acid, sulfate and citrate.