Effect of Water on the Chitosan Impregnation in SC–CO2 with Hydrophobic Diaryl Imidazoles and on the Kinetics of Their Subsequent Release in a Model Biological Medium

Abstract

Abstract—Sustained-release compositions based on chitosan and substituted diaryl imidazoles (DAIs) possessing antitumor activity were obtained in supercritical carbon dioxide (SC–CO2). It has been found that the use of water (0.17 vol %) as a co-solvent during SCF impregnation of chitosan with DAIs leads to an increase in the DAI content in the polymer matrix. Obviously, this is due to an increase in the degree of chitosan swelling in the SC–CO2 medium in the presence of water. It is interesting to note that the effect of water on the rate of release of the SCF-introduced DAIs from the matrix into a model medium with pH 1.6 is determined by the DAI structure. For the first time, it is shown that the solubilization of DAI molecules by Pluronic F-127 before their SCF introduction into the chitosan matrix can be used as an additional efficient way to prolong the action of matrix medicinal compositions.