Characterization of steroid/cyclodextrin inclusion compounds by x-ray powder diffractometry and thermal analysis

Two inclusion compounds, progesterone with beta- and gamma-cyclodextrin, were studied with X-ray powder diffractometry and thermal analysis. Disappearance of characteristic X-ray diffraction patterns of the two compounds as well as the appearance of a new diffraction pattern for each were found when formation of the inclusion compounds was completed. The X-ray diffraction patterns of beta-cyclodextrin measured at various temperatures showed a structural change occurring between 60 degrees C to 80 degrees C, which coincided well with the DSC endothermic peak around 75 degrees C. Results suggest that changes in the X-ray diffraction patterns of cyclodextrin during inclusion formation and during heating is due to the displacement of adsorbed water by progesterone in the cavity of cyclodextrin.