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Solid-state properties of warfarin sodium 2-propanol solvate
Agam R Sheth1, William W Brennessel, Victor G Young
1Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Weaver-Densford Hall, 308 Harvard Street SE, Minneapolis, Minnesota 55455-0343, USA.
Journal of Pharmaceutical Sciences
|September 25, 2004
Summary
Warfarin sodium 2-propanol solvate undergoes water uptake via deliquescence above 68% relative humidity (RH) without structural changes. Thermal stress causes amorphization and 2-propanol loss.
Area of Science:
- Solid-state chemistry
- Pharmaceutical science
- Crystallography
Background:
- Warfarin sodium 2-propanol solvate (W) is a crystalline form with pharmaceutical relevance.
- Understanding its stability under varying environmental conditions is crucial for drug formulation and storage.
Purpose of the Study:
- To investigate the effects of relative humidity (RH) and temperature on the molecular and crystal structure, and physical properties of warfarin sodium 2-propanol solvate (W).
Main Methods:
- Single crystal X-ray diffractometry
- Unit cell and volume computations
- Controlled humidity and temperature storage studies
Main Results:
- A critical RH of 60% < RH(0) <= 68% was identified, above which deliquescence occurs, initiating at the crystal surface.
- No change in crystal or molecular structure was observed during initial deliquescence stages.
- Water uptake does not involve exchange with 2-propanol within the crystal lattice.
- Thermal stress (120°C for 23h) induced amorphization and 2-propanol loss, potentially via an intermediate crystalline phase.
Conclusions:
- Warfarin sodium 2-propanol solvate exhibits distinct phase behavior influenced by RH and temperature.
- Deliquescence and thermal degradation mechanisms were elucidated at a molecular level, providing insights into solid-state stability.