Sodium aspirin salts: crystallization and characterization

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Búdová, Miroslava
Skořepová, Eliška
Jan, Čejka
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American Chemical Society
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Acetylsalicylic acid (trade name aspirin) is a well-known drug with antipyretic and analgesic effects. Mixtures that benefit from better solubility of its sodium salt have been sold for almost 90 years. Currently, several drug products are available with sodium aspirin as their active ingredient, but, until now, its crystal structure remained unknown. We have investigated the multicomponent system of sodium acetylsalicylate with the following results: an anhydrate and a dihydrate of a 1:1 salt were identified together with a hemihydrate of a 2:1 salt. Crystal structures of all forms were solved by single-crystal X-ray diffraction. The structural changes upon desolvation were studied by simultaneous thermogravimetric/differential scanning calorimetry supported by X-ray powder diffraction. The crystal structures were compared to those of all up-to-date published crystal structures of aspirin salts. Both of the hydrated sodium salts belong to the same isostructural family, while the anhydrate crystallizes with a unique packing of the acetylsalicylate anions.
Salts , Crystal structure , Molecules , Sodium cations , Polymorphism , Hydrates , Polymorphic transformation
Búdová, M., Skořepová, E. and Jan, Č. (2018) 'Sodium Aspirin Salts: Crystallization and Characterization', Crystal Growth & Design, 18(9), pp. 5287-5294. doi: 10.1021/acs.cgd.8b00718
© 2018 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Crystal Growth and Design, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see