A solution and solid state study on 2-hydroxypropyl-beta-cyclodextrin complexation with hyodeoxycholic acid

Hyodeoxycholic acid (HDCA) is a 6-alpha dihydroxylated natural bile acid ca pable of preventing gallstone formation by reducing the bile cholesterol sa turation. However, any attempt to enrich the bile acid pool with HDCA have failed owing to the poor solubility of the molecule. To resolve the bioavai lability problems, the complexation of HDCA into the HP beta CD cavity was studied in solution (solubility methods, C-13- and H-1-NMR spectroscopy and circular dichroism) and in the solid state (IR spectroscopy, X-ray diffrac tometry and thermal analysis). According to the results, the HDCA inclusion took place with 1 : 1 stoichiometry. The influence of different preparatio n methods of the solid complex was evaluated for its potential use in appro priate pharmaceutical formulations to improve the bioavailability of HDCA.