Perfusion calorimetry in the characterization of solvates forming isomorphic desolvates.

In this study, the potential of perfusion calorimetry in the characterization of solvates forming isomorphic desolvates was investigated. Perfusion calorimetry was used to expose different hydrates forming isomorphic desolvates (emodepside hydrates II-IV, erythromycin A dihydrate and spirapril hydrochloride monohydrate) to stepwise increasing relative vapour pressures (RVP) of water and methanol, respectively, while measuring thermal activity. Furthermore, the suitability of perfusion calorimetry to distinguish the transformation of a desolvate into an isomorphic solvate from the adsorption of solvent molecules to crystal surfaces as well as from solvate formation that is accompanied by structural rearrangement was investigated.

The study of different solid forms of Emodepside.

Emodepside is an endoparasiticide used in veterinary drugs. It exists in four different crystal forms which were characterised using DSC, TGA, evolved gas analysis (using FT-IR spectroscopy), hot-stage microscopy, FT-Raman, FT-IR and FT-NIR spectroscopy and powder X-ray diffraction. Thermal analysis showed that the forms II-IV contain considerable amounts of water being easily lost upon heating.