The influence of the preparation methods on the inclusion of model drugs in a β-cyclodextrin cavity

The work aims to prove the complexation of two model drugs (ibuprofen, IB and indomethacin, IN) by β-cyclodextrin (βCD), and the effect of water in such a process, and makes a comparison of their complexation yields. Two methods were considered: kneading of a binary mixture of the drug, βCD, and inclusion of either IB or IN in aqueous solutions of βCD. In the latter method water was removed by air stream, spray-drying and freeze-drying. To prove the formation of complexes in final products, optical microscopy, UV spectroscopy, IR spectroscopy, DSC, X-ray and NMR were considered. Each powder was added to an acidic solution (pH = 2) to quantify the concentration of the drug inside βCD cavity. Other media (pH = 5 and 7) were used to prove the existence of drug not complexed in each powder, as the drugs solubility increases with the pH. It was observed that complexation occurred in all powders, and that the fraction of drug inside the βCD did not depend neither on the method of complexation nor on the processes of drying considered.