Leaching of pectin from mixed films containing pectin, chitosan and HPMC intended for biphasic drug delivery.

Mixed films containing pectin, chitosan and HPMC, prepared by solvent casting from 0.1 M HCl (pH 1.5) and 0.1 M acetic acid (pH 2.9) were evaluated for their morphological and leaching properties. Films cast at pH 1.5 were uniform with smooth surfaces while films cast at pH 2.9 showed particle aggregation and had rough surfaces due to polyelectrolyte complex (PEC) formation between pectin and chitosan in the medium. The leaching of pectin was higher from films at cast pH 1.5 due to the absence of PEC formation. Pectin leaching was controlled in simulated upper gastrointestinal conditions but was accelerated in the presence of pectinolytic enzymes. The leaching of pectin from the mixed films was a function of the pH of the film casting solvent, pH of the incubation medium, PEC formation and HPMC content.