Effect of Pullulan as Additive to the Synthetic Polymeric Coating Blend Eudragit® NM-L55 on the Properties of the Resulting Films.

The aim of the present study was to investigate the effect of pullulan as additive to Eudragit® NM-L55 blend film for modification of the resulting film properties with regard to future drug release studies. Films of the plain polymers as well as of those of their blends at different ratios were prepared by an aqueous casting method. Infrared, mechanical, thermogravimetric, water vapor permeance and swelling index studies were performed with blend films of Eudragit® NM-L55 and pullulan. It was demonstrated that intermolecular interactions between Eudragit® NM-L55 and pullulan did not exist. An increasing fraction of up to 30% pullulan in the Eudragit® NM-L55 blend film led to films with rising tensile strength, increasing Young's modulus, and decreasing elongation at break. With increasing fraction of pullulan in the blend films, the thermal stability thereof decreased up to around 400°C. Because of the high hydrophilicity of pullulan, the water vapor permeance increased with increasing fraction of pullulan in the blend films. The addition of pullulan influenced the swelling behavior of the blend films at pH 1.2 and 6.8. The higher the fraction of pullulan in the blend films the earlier the films eroded. These results demonstrate that the polysaccharide pullulan had a major impact on the Eudragit® NM-L55 blend film. It turned out that a fraction of up to 20% pullulan in the synthetic blend film is appropriate to be applied as a coating material. Thus, suitable film properties may be obtained by adjusting the fraction of pullulan in the Eudragit® NM-L55 blend film.