Studies on drug release from pectin/ethylcellulose film-coated tablets: a potential colonic delivery system

Combinations of pectin and ethylcellulose, when applied as a film coat, have potential value as a colonic delivery system. Aqueous dispersions of pectin and ethylcellulose were used to film coal paracetamol tablet cores. Drug release mechanisms were assessed using flow through dissolution testing in the presence and absence of enzymes. Drug release from the coated systems was complex and depended on the nature and characteristics of the mixed film as well as the composition of the dissolution medium. Drug release profiles were compatible with a mechanism involving the formation of channels in the film caused by pectin dissolution. Channel formation was in most cases accelerated by the presence of pectinolytic enzymes showing that the pectin in the mixed film was susceptible to enzymic attack. Pectin, ethylcellulose combinations may have value as film coating preparations for colonic delivery. Formulation effects and mechanisms of drug release have been identified as a basis for further studies. (C) 1997 Elsevier Science B.V.