Tigecycline Crystallization via Solvent Exchange
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Solution Overview
Problem
Current methods for preparing tigecycline result in amorphous forms, which lack desirable solid state physical properties such as flowability and dissolution rates, necessitating the use of glidants and affecting storage stability and therapeutic efficacy.
Innovation Solution
Development of methods to obtain crystalline forms I and II of tigecycline through solvent exchange processes involving dichloromethane with esters or ketones, followed by cooling and slurrying, to achieve specific XRD and 13C NMR characteristics, and controlled water content, enhancing chemical and physical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tigecycline is prepared by conventional evaporation from dichloromethane solution, then the drug substance can be obtained, but it forms an amorphous solid with poor flowability and dissolution rates
Solution Approach 1:
The patent applies parameter changes by controlling crystallization conditions including solvent selection (ethyl acetate, acetone, or acetonitrile), temperature ranges (cooling from room temperature to 0-10°C), and pH adjustment (pH 4-6) to transform tigecycline from an amorphous solid to specific crystalline forms (Form I or Form II) with improved flowability and stability
Solution Approach 2:
The patent utilizes phase transitions by inducing crystallization from solution through controlled cooling and solvent exchange, transforming tigecycline from an amorphous phase to ordered crystalline phases (Form I or Form II), which fundamentally changes the solid-state properties including flowability, dissolution rate, and storage stability
2Productivity
If tigecycline is prepared by conventional evaporation from dichloromethane solution, then the drug substance can be obtained, but it forms an amorphous solid with poor dissolution rates
Solution Approach 1:
The patent applies parameter changes by controlling crystallization conditions including solvent selection (ethyl acetate, acetone, or acetonitrile), temperature ranges (cooling from room temperature to 0-10°C), and pH adjustment (pH 4-6) to transform tigecycline from an amorphous solid to specific crystalline forms (Form I or Form II) with improved flowability and stability
Solution Approach 2:
The patent utilizes phase transitions by inducing crystallization from solution through controlled cooling and solvent exchange, transforming tigecycline from an amorphous phase to ordered crystalline phases (Form I or Form II), which fundamentally changes the solid-state properties including flowability, dissolution rate, and storage stability
3Ease of operation
If glidants are added to improve flowability, then handling during processing is improved, but the formulation complexity and cost increase
Solution Approach 1:
The patent applies the taking out principle by removing the need for glidant additives through direct crystallization of tigecycline into Forms I or II, which inherently possess excellent flowability properties, thereby simplifying the formulation and eliminating additional excipients
Solution Approach 2:
The patent applies the self-service principle by designing a crystallization process that produces tigecycline with self-improved flowability characteristics, where the crystalline structure itself provides the desired handling properties without requiring external additives or modifications
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 crystalline forms exhibit improved flowability, dissolution rates, and storage stability, providing a more efficient and stable pharmaceutical product with targeted release profiles.
Implementation Method 1
solvent exchange processes involving dichloromethane with esters or ketones
Implementation Method 2
cooling and slurrying, to achieve specific XRD and 13C NMR characteristics
Implementation Method 3
cooling the suspension to obtain tigecycline form II
Data Source
AI summary
The present invention provides processes for the preparation of crystalline forms of Tigecycline.