Physical changes of beta-sitosterol crystals in oily suspensions during heating

Research output: Contribution to journalJournal articleResearchpeer-review

Anna von Bonsdorff-Nikander, Satu Lievonen, Leena Christiansen, Milja Karjalainen, Jukka Rantanen, Jouko Yliruusi

The aim of this research was to describe the thermal behavior of beta-sitosterol crystals in oil-suspensions with a focus on the role of water during heating. The suspensions were prepared by recrystallization in order to achieve a microcrystalline particle size. The structural changes together with the mechanical properties of the suspensions during heating were studied by using variable temperature X-ray powder diffractometry (VT-XRPD), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). Hydrated beta-sitosterol crystals in an oil-suspension dehydrated, despite the composition of the suspensions, at low temperatures. At high beta-sitosterol concentration, the monohydrate crystal form changed partially to a hemihydrated form, and when only a small amount of water was initially incorporated, the hemihydrate crystal form dehydrated to a mostly anhydrate crystal form. The released water, which was immiscible in the surrounding oil, caused the recrystallization of hydrated beta-sitosterol during cooling. This procedure indicated a reversible dehydration process. Structural and thermal analysis of beta-sitosterol crystals in suspensions, together with mechanical analysis made it possible to understand various physical changes during heating.

Original languageEnglish
JournalAAPS PharmSciTech
Volume6
Issue number3
Pages (from-to)E413-20
ISSN1530-9932
DOIs
Publication statusPublished - 2005

ID: 140621755