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 digest ibility properties of water-miscible organic solvent-based amylose-ethylcel lulose films as potential coatings for colonic drug delivery. Free films co ntaining different ratios of amylose to ethylcellulose were cast from the w ater-miscible organic solvent, ethyl lactate, in combination with the plast iciser, dibutyl sebacate. The resultant mixed films were characterised in t erms of tensile strength and elasticity, polymer miscibility, permeability, and digestibility under simulated colonic conditions. Films containing hig her concentrations of amylose displayed increasing weakness and softness an d faster permeation to hydrogen ions compared to films with lower amylose c ontent. No apparent miscibility was detected between the amylose and ethylc ellulose, regardless of film composition. The films were found to be suscep tible to digestion by bacterial enzymes within a simulated colonic environm ent. The extent of digestion was directly proportional to the amount of amy lose present within the film. Overall, the results suggest that such amylos e-ethylcellulose films could be used as coatings for drug delivery to the c olon. (C) 2000 Elsevier Science B.V. All rights reserved.