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Published on: August 9, 2022
Thermodynamic stability and crystal structures for polymorphs and solvates of formoterol fumarate
K Jarring1, T Larsson, B Stensland
1Analytical Development, Pharmaceutical & Analytical R&D, AstraZeneca R&D Lund, S-221 87 Lund, Sweden.
Abstract:
Polymorph screening of formoterol fumarate was performed in 12 solvents, followed by evaluations of thermodynamic stability. Three anhydrates, a dihydrate, a diethanolate, a diisopropanolate, and a dibensylalcoholate were found. The crystal structure of three solvated modifications and of the most stable anhydrate was investigated. This indicated that solvation is needed to get a stable and well packed crystal structure. Thermodynamic testing suggests that five crystal modifications are thermodynamically stable, at different conditions, since they are all reversibly related to each other.
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