Characterization of ethylcellulose: starch-based film coatings for colon targeting

Background: The site-specific delivery of drugs to the colon can be highly advantageous for various applications, including the local treatment of inflammatory bowel diseases. The aim of this study was to provide efficient tools that can be used to easily adjust the key properties of novel polymeric film coatings allowing for colon targeting. Methods: Free films based on blends of ethylcellulose and different types of starch derivatives ( partially being pregelatinized, acetylated, and/or hydroxypropylated) were prepared and characterized. Results: The key properties of the polymeric systems can effectively be adjusted by varying the polymer blend ratio and type of starch derivative. This includes the water uptake and dry mass loss kinetics as well as the mechanical properties of the films before and upon exposure to aqueous media simulating the contents of the upper GIT. Conclusion: Broad ranges of film coating properties can easily be provided, being adapted to the needs of the respective drug treatment.