Diversity of felodipine solvates: structure and physicochemical properties

Abstract

Solvates of the calcium-channel blocking agent felodipine with three structurally related common organic solvents, acetone (ATN), dimethyl sulfoxide (DMSO) and acetophenone (APN), are described. A relationship between the felodipine packing arrangement in all known solvates and the van der Waals volume of the solvent molecule is established. Intermolecular interaction energies in the crystals are examined using the PIXEL approach in order to rationalize the difference between alternative molecule packing arrangements. DSC studies show that the desolvation onset temperatures of the solvates are closely comparable, despite the large difference in the boiling points of the solvent molecules. The enthalpies of formation derived from the calorimetric data for the solvates are also found to be similar, despite the difference in the van der Waals volume of the solvent molecules.