Naloxone-DMF Solvate Crystallization for High-Purity Production

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Solution Overview

Problem

Existing methods for producing naloxone in larger quantities are complex, energy-intensive, and result in high waste production, with unsatisfactory yields and purity, making them unsuitable for pharmaceutical use.

Innovation Solution

The use of a crystalline naloxone-dimethylformamide solvate as a reagent in a method involving seeding or spontaneous precipitation in a dimethylformamide medium, followed by solvent treatment to release naloxone, reduces the number of steps, energy consumption, and waste, while enhancing purity and yield.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If complex separation and purification steps are used to isolate naloxone in larger quantities, then the quantity of naloxone obtained is improved, but energy consumption increases and synthesis time increases

Engineering Contradiction:
Improvequantity of naloxoneVSAvoidenergy consumption
Core Design Contradiction:
Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

The patent extracts the purification function from multiple complex steps and concentrates it into a single crystallization step. By forming a solvate complex with DMF, the naloxone is selectively precipitated from the reaction mixture, separating it from impurities in one operation rather than requiring multiple separation steps.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the physical-chemical parameters of the system by introducing DMF as a solvent and forming a solvate complex. This parameter change enables the naloxone to precipitate in a different physical state (solvate form) with distinct solubility characteristics, allowing for efficient separation and purification in a single step.

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If complex separation and purification steps are used to isolate naloxone in larger quantities, then the quantity of naloxone obtained is improved, but synthesis time increases

Engineering Contradiction:
Improvequantity of naloxoneVSAvoidsynthesis time
Core Design Contradiction:
Quantity of substanceVSLoss of time

Solution Approach 1:

The patent merges multiple separation and purification operations into a single crystallization step. By combining filtration, washing, and crystallization into one integrated operation, the process eliminates the time required for multiple separate purification steps while maintaining high quantity and purity of naloxone.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent performs preliminary action by forming the solvate complex during the reaction itself, which pre-separates the naloxone from impurities before the workup step. This preliminary separation action eliminates the need for subsequent complex purification steps, reducing overall synthesis time.

Inventive Principle:
Principle #10Preliminary action

3Quantity of substance

If complex separation and purification steps are used to isolate naloxone in larger quantities, then the quantity of naloxone obtained is improved, but waste material production increases

Engineering Contradiction:
Improvequantity of naloxoneVSAvoidwaste material
Core Design Contradiction:
Quantity of substanceVSLoss of substance

Solution Approach 1:

The patent converts the potentially harmful effect of impurities in the reaction mixture into a beneficial selective precipitation effect. By exploiting the different solubility characteristics of naloxone-DMF solvate versus impurities, the process selectively precipitates only the desired product, converting what would be waste into a useful separation mechanism.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent discards the DMF solvent after the crystallization step, which carries away the impurities with it. The naloxone-solvate complex is recovered in high purity form, and the DMF can be recovered and reused, minimizing waste generation while maintaining high quantity and purity of the final product.

Inventive Principle:
Principle #34Discarding and recovering

4Reliability

If conventional methods are used for producing naloxone, then the process is established, but the final yield is not completely satisfactory

Engineering Contradiction:
Improveprocess reliabilityVSAvoidfinal yield
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent changes the reaction parameters by using DMF as a solvent and forming a solvate complex, which improves the final yield. The solvate formation shifts the equilibrium and enables more complete conversion of the starting material, while the crystallization step ensures high purity, thus improving both reliability and productivity.

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

This method allows for the production of naloxone in higher purity and yield with reduced energy consumption and waste, making it suitable for pharmaceutical use.

Implementation Method 1

stirring the first reaction mixture received in step S2) for a time period sufficient for a second amount of crystalline naloxone-dimethylformamide solvate (according to the present invention as described herein or as described herein as being preferred) to precipitate as a solid

Methodology Applied
Scientific EffectPrecipitation: Precipitation

Implementation Method 2

adding to the crystalline naloxone-dimethylformamide solvate received in step S3) as precipitated solid a solvent or solvent mixture suitable to release naloxone of formula I from said crystalline naloxone-dimethylformamide solvate

Methodology Applied
Scientific EffectSolvation: Solvation

Data Source

PatentEP4686721A1Crystalline naloxone-dimethylformamide solvate, methods for its preparation and its use as a reagent in a method of making naloxone
Publication Date: 2026.02.04 SIEGFRIED AG
  • EP4686721A1 patent drawingFigure 1
  • EP4686721A1 patent drawingFigure 2
  • EP4686721A1 patent drawingFigure 3a

AI summary

Described herein is a crystalline naloxone-dimethylformamide solvate and methods of making a first and a second amount thereof, as well as methods of making naloxone or a naloxone salt, involving said crystalline naloxone-dimethylformamide solvate. Further described herein is the use of dimethylformamide for preparing said crystalline naloxone-dimethylformamide solvate and the use of said crystalline naloxone-dimethylformamide solvate as a reagent for i.a. purifying naloxone. Moreover, it is described a crystalline naloxone and a mixture comprising dimethylformamide and said crystalline naloxone-dimethylformamide solvate. Naloxone has the following formula I: