The properties of amylose-ethylcellulose films cast from organic-based solvents as potential coatings for colonic drug delivery.

The purpose of the study was to establish the physico-mechanical and digestibility properties of water-miscible organic solvent-based amylose-ethylcellulose films as potential coatings for colonic drug delivery. Free films containing different ratios of amylose to ethylcellulose were cast from the water-miscible organic solvent, ethyl lactate, in combination with the plasticiser, dibutyl sebacate. The resultant mixed films were characterised in terms of tensile strength and elasticity, polymer miscibility, permeability, and digestibility under simulated colonic conditions. Films containing higher concentrations of amylose displayed increasing weakness and softness and faster permeation to hydrogen ions compared to films with lower amylose content. No apparent miscibility was detected between the amylose and ethylcellulose, regardless of film composition. The films were found to be susceptible to digestion by bacterial enzymes within a simulated colonic environment. The extent of digestion was directly proportional to the amount of amylose present within the film. Overall, the results suggest that such amylose-ethylcellulose films could be used as coatings for drug delivery to the colon.