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Updated: Aug 14, 2026

A Package of Established Analytical Tools to Investigate the Solid-State Alteration of Lipid-Based Excipients
Published on: August 9, 2022
Physical changes of beta-sitosterol crystals in oily suspensions during heating
Anna von Bonsdorff-Nikander1, Satu Lievonen, Leena Christiansen
1Division of Pharmaceutical Technology, Faculty of Pharmacy, University of Helsinki. anna.vonbonsdorff@helsinki.fi
Abstract:
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.
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