Inclusion Complexes of Cyclodextrins with Cinnamic Acid Derivatives: Dissolution and Thermal Behavior

Abstract

Typical Bs type phase solubility diagrams were obtained for α- and β-cyclodextrins (a-CyD and β-CyD) with methyl cinnamate, ethyl cinnamate, and cinnamaldehyde in water at 25°. Solid complexes for a- and β-CyDs with three guest molecules were obtained and their molar ratios were found to be 2:1 (a-CyD/guest molecule) and 1: 1 (β-CyD/guest molecule), respectively. In sharp contrast, apparent stability constant (Kc' x2018;) and dissolution rate ' x2018;)of a-CyD complexes were larger than those of β-CyD complexes. The thermal gravimetric analysis thermogram showed that the volatility of the guest molecule was lowered by the formation of CyD inclusion complex. © 1979, The Pharmaceutical Society of Japan. All rights reserved.