Sorption of pindolol and related compounds by a β-cyclodextrin polymer: Isosteric heat of sorption

The possibility of using cyclodextrin polymers in drug delivery makes it necessary an investigation of their mechanisms of interaction with different solutes. In this sense, the sorption of pindolol, propranolol, indole and 4-methoxyindole on a crosslinked polymer containing β-cyclodextrin has been studied. The similar rapid kinetic profiles obtained for the four solutes can be related to the high swelling capacity of the polymer, which enables the expansion of its network and the diffusion process. The differences detected in the sorption capacities of the solutes are associated to their ability to form inclusion complexes within the cyclodextrin cavities. The sorption isosteric heats determined evidence the heterogeneity of the polymer, with the cyclodextrin cavity being the most favourable adsorption site.