Characterization of polymorphic solid-state changes using variable temperature X-ray powder diffraction

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Milja Karjalainen, Sari Airaksinen, Jukka Rantanen, Jaakko Aaltonen, Jouko Yliruusi

The aim of this study was to use variable temperature X-ray powder diffraction (VT-XRPD) to understand the solid-state changes in the pharmaceutical materials during heating. The model compounds studied were sulfathiazole, theophylline and nitrofurantoin. This study showed that the polymorph form of sulfathiazole SUTHAZ01 was very stable and SUTHAZ02 changed as a function of temperature to SUTHAZ01. Theophylline monohydrate changed via its metastable form to its anhydrous form during heating and nitrofurantoin monohydrate changed via amorphous form to its anhydrous form during heating. The crystallinity of SUTHAZ01, SUTHAZ02 and theophylline monohydrate were very high and stable. Nitrofurantoin monohydrate was also very crystalline at room temperature but during heating at lower temperatures the crystallinity decreased and started to increase strongly at the temperature where the sample had changed to the anhydrous form. The average crystallite size of sulfathiazole samples varied only a little during heating. The average crystallite size of both theophylline and nitrofurantoin monohydrate decreased during heating. However, the average crystallite size of nitrofurantoin monohydrate returned back to starting size at higher temperatures. These analyses showed that VT-XRPD can be used to effectively characterize polymorphic changes during heating.

Original languageEnglish
JournalJournal of Pharmaceutical and Biomedical Analysis
Volume39
Issue number1-2
Pages (from-to)27-32
Number of pages6
ISSN0731-7085
DOIs
Publication statusPublished - 1 Sep 2005

ID: 140622016