The resulting thin film was dissolved by adding water (Millipore). In the resulting solution, the polymer concentration was kept at 10 g/L, while increasing the drug concentration from 1 g/L to 10 g/L in each series. The actual drug concentration achieved in the aqueous phase was assessed using HPLC or UV spectroscopy using a microplate reader after removal of non-solubilized drug, if any, by centrifugation.