Collect. Czech. Chem. Commun. 2011, 76, 553-566
Published online 2011-04-29 13:18:47

Investigations on the polymorphism and pseudopolymorphism of clobetasone butyrate

Christian Näther* and Inke Jeß

Institut für Anorganische Chemie der Christian-Albrechts-Universität zu Kiel, Max.-Eyth.-Str. 2, 24118 Kiel, Germany


Clobetasone butyrate was investigated for polymorphism and pseudopolymorphism. Solvent mediated conversion experiments reveal that the commercially available form I represent the thermodynamically most stable form at room temperature and DSC measurements shows that it should also be the most stable form until melting. Form I crystallizes in space group P212121 with three crystallographically independent molecules of similar conformation. From methanol an additional pseudo polymorphic form was discovered. In the crystal structure (space group P212121) the solvent molecules are connected to the clobetasone butyrate molecules by O–H···O hydrogen bonding. Investigations of the solvate using thermogravimetry, differential thermoanalysis as well as differential scanning calorimetry proves, that on solvent removal an amorphous form is obtained that crystallizes into form I on further heating.

Keywords: Clobetasone butyrate; Polymorphism; Pseudopolymorphism; Crystal structures; Thermoanalytical methods; Crystal growth; Calorimetry; X-Ray diffraction.

References: 35 live references.