Different types of Eudragit films containing warfarin were prepared by solvent casting on a glass plate (Lin et al., 1991). The weight ratio of warfarin to Eudragit was 1:0.5, 1:1.5 and 1:3; each of them was completely dissolved in acetone. Acetone was first evaporated at room temperature and then was vacuum dried for 24 h at 60°C, and stored in a sealed container until use.