Purpose: The purpose of the study was to investigate the potential of pectin, ethylcellulose combinations as a practical film coating for colonic delivery.
Methods: Combinations of pectin and ethylcellulose, in the form of an aqueous dispersion, were used as coating formulations. Paracetamol cores were used as the substrate. The coatings were assessed by a flow through dissolution system simulating in vivo conditions by changes in pH and residence time. Pectinolytic enzymes were used to simulate the bacterial flora of the colon.
Results: Drug release was controlled by the ratio of ethylcellulose to pectin in the film coat. Increasing the proportion of ethylcellulose and increasing the coat weight reduced drug release in pH1 and pH7.4 media. The addition of pectinolytic enzymes to pH6 media increased the release of drug.
Conclusions: Combinations of ethylcellulose and pectin can provide protection to a drug in the upper g.i. tract while allowing enzymatic breakdown and drug release in the colon.