Effect of supercritical carbon dioxide on the loading and release of model drugs from polyurethane films: comparison with solvent casting

Thermoplastic polyurethanes (TPUs) are widely used in biomedical applications because of their excellent mechanical properties and biocompatibility. However, their role as possible matrices for drug delivery has received little attention. In this study, the loading and release of model drugs from different TPUs using supercritical CO 2 (scCO 2 ) as an inert and convenient solvent are investigated. The effects of scCO 2 treatment on the physical properties of ElastEon TPU films are assessed. The results indicate subtle effects on the microphase morphology of the TPU without significant changes in its mechanical properties. Model drugs (rhodamine B, fluorescein, and 7-hydroxycoumain) are readily loaded into the films and show homogeneous impregnation across the thickness of the film. The loading capacity under the conditions used in the present study varies from less than 1% for rhodamine B to approximately 4% for 7-hydroxycoumarin. The release kinetics not only vary between the different drugs, but are also altered by changes in the composition of the hard and soft segments of the TPUs. These results demonstrate the potential of scCO 2 treatment in preparing drug-loaded polyurethanes used in medical devices. This information may be helpful in designing TPUs with different drug-release profiles for a variety of disease treatments