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Crystal structure and physical properties of two polymorphs of ropivacaine HCl
Per-Olov Bergström1, Andreas Fischer, Lars Kloo
1Preformulation and Biopharmaceutics AstraZeneca R & D, Södertälje, Sweden. per-olov.bergstrom@astrazeneca.com
Abstract:
The crystal structure of two polymorphs of ropivacaine HCl have been determined, as well as their relative stability up to 100 degrees C. A geometric restriction for a solid-state transition between the two polymorphs has been identified. The packing density along the H-bonded chains form the basis for a model explaining the kinetic crystallization of the metastable form. The difference in stability and physicochemical properties between the two polymorphs can be attributed to the difference in crystal structure.
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