Complexation of ursodeoxycholic acid with β-cyclodextrin–choline dichloride coprecipitate

The inclusion complexes of ursodeoxycholic acid (UDCA) with β-cyclodextrin (βCD) coprecipitated with choline dichloride (CDC) or β-cyclodextrin were investigated to evaluate the effect of the presence of choline for UDCA inclusion in βCD. The inclusion complexes were investigated in solution by phase solubility diagrams and ¹H NMR spectrometry and in solid state (kneading, freeze-drying, sealed heating and spray-drying) by DSC, SEM, HSM, XRD and IR spectroscopy. Stability constants were determined at pH 5.5 and 7.0 to simulate the environmental pH of the first intestinal tract and at different temperatures (25, 30 and 37°C) to obtain the thermodynamic parameters of inclusion. Both βCD–CDC and βCD increased the water solubility of UDCA particularly βCD–CDC. All complexes showed a high dissolution rate particularly the spray-dried complexes obtained in the presence of βCD–CDC.