Ibandronate Polymorph B Crystallization
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Solution Overview
Problem
The existing polymorph forms of Ibandronate, a potent anti-resorptive drug, have not been adequately characterized or efficiently produced, particularly for the more stable polymorph B, which is harder to separate during production, affecting its solubility and pharmaceutical applications.
Innovation Solution
The identification and characterization of crystalline Ibandronate polymorph B, along with a process involving crystallization in a polar solvent at specific temperatures, using polar aprotic solvents like acetone or tetrahydrofuran, to achieve a high yield of polymorph B for use as an anti-resorptive drug.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If polymorph A is used, then thermodynamic stability is improved, but ease of separation deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying crystallization conditions (temperature, solvent composition, pH) to obtain polymorph B instead of the thermodynamically stable polymorph A. Specifically, crystallization is performed at lower temperatures (0-10°C) and controlled pH ranges (4.5-5.5) to kinetically favor polymorph B formation, resolving the contradiction between stability and ease of separation.
Solution Approach 2:
The patent uses preliminary action by adding seed crystals of polymorph B before completion of crystallization to guide the crystallization process toward the desired polymorph. This pre-introduction of the target crystal structure ensures polymorph B formation even when polymorph A would otherwise be thermodynamically favored, thereby improving ease of separation while maintaining adequate stability.
2Ease of manufacture
If polymorph B is used, then ease of separation is improved, but thermodynamic stability deteriorates
Solution Approach 1:
The patent modifies crystallization parameters (lower temperature 0-10°C, controlled pH 4.5-5.5, specific solvent ratios) to kinetically trap polymorph B before it can convert to the more stable polymorph A. This parameter optimization allows polymorph B to be obtained with at least 80% purity directly from crystallization, improving ease of separation while accepting reduced thermodynamic stability.
Solution Approach 2:
The patent introduces seed crystals of polymorph B into the crystallization mixture at an early stage to template and guide crystal formation. This preliminary action ensures that polymorph B nucleates and grows preferentially, achieving high purity (≥80%) of the easily separable polymorph B form, thereby resolving the contradiction between stability and separation ease.
3Ease of manufacture
If conventional crystallization methods are used, then production cost is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The patent optimizes conventional crystallization parameters (temperature 0-10°C, pH 4.5-5.5, solvent composition with polar aprotic solvents like acetone or ethyl methyl ketone) to achieve selective formation of polymorph B. These parameter changes enable direct crystallization of high-purity polymorph B (≥80%) using standard equipment and procedures, maintaining low production cost while achieving high manufacturing precision.
Solution Approach 2:
The patent incorporates preliminary seeding with polymorph B crystals into the conventional crystallization process. This simple, low-cost seeding step directs crystal formation toward the desired polymorph B structure, achieving at least 80% purity without requiring complex purification steps, thereby maintaining cost-effectiveness while improving polymorph purity precision.
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 process allows for the isolation and characterization of Ibandronate polymorph B with a solubility of about 279 g/l, enhancing its use as an effective anti-resorptive drug for treating bone and calcium metabolic diseases like osteoporosis and Paget's disease, with a content of at least 80% polymorph B.
Implementation Method 1
The identification and characterization of crystalline Ibandronate polymorph B, along with a process involving crystallization in a polar solvent at specific temperatures
Data Source
AI summary
The present invention relates to a new crystalline polymorph of 3-(N-methyl-N-pentyl) amino-1-hydroxypropane-1,1-diphosphonic acid monosodium salt monohydrate (Ibandronate) with the following formula