Solvent-Free Gadolinium Contrast Agent Stability
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Solution Overview
Problem
Current MRI contrast agents, particularly those containing Gd(III), face issues with thermodynamic stability, leading to the release of toxic Gd(III) ions due to pH variations during manufacturing and injection, which can result in nephrogenic systemic fibrosis and other safety concerns.
Innovation Solution
A solvent-free gadolinium complex formulation with meglumine, synthesized in a one-step process that maintains a hydrated state, reducing the formation of non-gadolinium complexes and solvent impurities, and stabilizing the Gd(III)-ligand complex, thereby enhancing thermodynamic stability and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If solvent purification is used to remove impurities during manufacturing, then product purity is improved, but product stability deteriorates due to unpredictable ligand removal and large pH range variations
Solution Approach 1:
The patent extracts and eliminates solvents from the drug product formulation entirely. By using alternative purification methods that do not require solvent-based precipitation and drying, the invention removes the source of pH variability and ligand loss, thereby maintaining both purity and stability without the trade-off present in conventional methods
Solution Approach 2:
The patent changes the pH parameter control strategy by eliminating the root cause of pH variability (solvent purification process). This results in a dramatically narrowed pH range (7.0-7.5) compared to conventional methods, improving both manufacturing precision and product stability simultaneously
2Reliability
If large excess of ligand is used to reduce free Gd(III) ion formation, then safety is improved, but manufacturing complexity increases due to extensive solvent purification requirements
Solution Approach 1:
The patent extracts solvents from the manufacturing process, eliminating the need for extensive solvent purification steps. This simplification allows the use of ligand excess for safety without introducing the manufacturing complexity that would otherwise be required to handle solvent-impurity interactions
Solution Approach 2:
The patent uses meglumine as an intermediary substance to control pH and stabilize the Gd(III)-ligand complex. This mediator allows for precise pH control (7.0-7.5) without requiring solvent-based purification, thereby maintaining safety through controlled ligand-Gd(III) interaction while simplifying the manufacturing process
3Ease of manufacture
If multi-step process with drying and reformulating is used to prepare gadolinium complex, then product formulation is achieved, but thermodynamic stability deteriorates due to dramatic pH shifts and gadolinium-ligand balance disruption
Solution Approach 1:
The patent merges multiple steps (complex formation, pH adjustment, and formulation) into a single integrated aqueous process. By maintaining the hydrated state throughout and eliminating drying/reformulating steps, the invention prevents dramatic pH shifts and preserves the gadolinium-ligand balance, thereby achieving both ease of manufacture and thermodynamic stability
Solution Approach 2:
The patent maintains continuous aqueous conditions throughout the manufacturing process, avoiding interruption by drying and reformulating steps. This continuity preserves the thermodynamic stability of the Gd(III)-ligand complex by preventing pH shifts and metal ion release that occur during phase transitions
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 approach results in a gadolinium contrast agent with improved safety, reduced variability, and enhanced stability, minimizing the risk of nephrogenic systemic fibrosis and maintaining a stable pH range, while eliminating solvent contaminants and impurities.
Implementation Method 1
Paramagnetic metal chelates, such as Gd(III)-diethylenetriaminepentaacetic acid (Gd(III)-DTPA) (Magnevist), Gd(III)-N,N′,N′,N′′,N′′′-tetracarboxymethyl-1,4,7,10-tetraaza cyclododecane (Gd(III)-DOTA), and their analogs have proven to increase the relaxation rate of surrounding protons
Data Source
AI summary
Disclosed herein are complexes of gadolinium metal, ligand and meglumine that are substantially free of non-aqueous solvents. In particular, solvent-free complexes of 1) gadopentetate dimeglumine and 2) gadoterate meglumine are disclosed and methods of their preparation are disclosed. In addition, methods are disclosed for purifying reactants, monitoring and controlling pH, quantifying the free gadolinium content, quantifying the concentration of gadolinium-ligand complex in aqueous solution, and procedures for producing a drug product in one step. The one step process eliminates the need to dry the gadolinium-ligand complex, which is typically highly hygroscopic. The one step process includes purification steps that do not require the use of non-aqueous solvents.