An Investigation into the Dehydration Behavior of Paroxetine HCl Form I Using a Combination of Thermal and Diffraction Methods:The Identification and Characterization of a New Anhydrous Form

Pina, M. Fátima, Zhao, Min, Pinto, João F., Sousa, João J., Frampton, Christopher S., Diaz, Victor, Suleiman, Osama, Fábián, László and Craig, Duncan Q. M. (2014) An Investigation into the Dehydration Behavior of Paroxetine HCl Form I Using a Combination of Thermal and Diffraction Methods:The Identification and Characterization of a New Anhydrous Form. Crystal Growth & Design, 14 (8). pp. 3774-3782. ISSN 1528-7483

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Abstract

Paroxetine HCl can exist as a nonstoichiometric hydrate (Form II) or as a stoichiometric hemihydrate (Form I); the latter is considered to be the stable form and its structure is well-known. However, little work has been performed to investigate its dehydration behavior; hence, the generation of the anhydrous form via dehydration of Form I was investigated. A combination of thermal (differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)) and diffraction (variable-temperature X-ray powder diffraction (VT-XRPD)) techniques was used. Dehydrated Form I was prepared using ultradry conditions, and the resulting product was compared to dehydrated Form II. DSC indicated that the two dehydrated forms of Forms I and II had distinct melting points. TGA experiments allowed the calculation of the activation energy for the dehydration of Form I, which varies between 86 and 114 kJ/mol. Pawley refinement of the VT-XRPD data suggested that Form I dehydrates to an isostructural anhydrate, since the unit cell parameters of this new form were very similar to those of Form I with only a smaller volume as a consequence of dehydration. Comparison with dehydrated Form II indicated that these two forms represent different crystal entities; hence, a new anhydrous form of paroxetine HCl has been identified.

Item Type: Article
Faculty \ School: Faculty of Science > School of Pharmacy
Depositing User: Pure Connector
Date Deposited: 19 Aug 2014 09:10
Last Modified: 06 May 2020 23:49
URI: https://ueaeprints.uea.ac.uk/id/eprint/49934
DOI: 10.1021/cg500150r

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