Mesomorphous versus traces of crystallinity: The itraconazole example

•Characterizing partially disordered pharmaceuticals is very challenging due to the fact that more than one discrete disordered phase can be present.•Dynamic mechanical analysis and dielectric analysis are extremely helpful in characterizing pharmaceutical mesophases (liquid crystals).•Thermotropic pharmaceutical mesophases, often mistaken as amorphous or partially crystalline, can show different phases of liquid crystallinity at different temperature.•Liquid crystalline pharmaceutical materials often show amorphous behavior along with other characteristics specific to mesomorphous materials.•The thermal and mechanical history of pharmaceutical disordered samples has a significant effect on their phase composition.

Characterizing disordered pharmaceutical materials can be challenging, especially materials with partially disordered structures that lose one or two directional order (mesophases) and do not fit the traditional characterization categories of amorphous, crystalline or a combination of the two. Itraconazole, an antifungal agent, was chosen as a model compound that, when quench cooled, exhibits atypical disordered structure. Five different analytical tools were used to map out the molecular structure of this material and how it changes with changing temperature. X-ray diffraction showed some remnant crystallinity while dielectric analysis, dynamic mechanical analysis, DSC and hot stage microscopy gave more detailed molecular structure of the disordered material and explained all temperature related structural changes.The characterization of mesomorphous Itraconazole described here will help characterize a wide range of pharmaceuticals that exhibit thermotropic (temperature induced) mesomorphism at the molecular level.