Biphasic drug release: the permeability of films containing pectin, chitosan and HPMC

The permeabilities of mixed films of pectin/chitosan/HPMC have been studied to assess their value in producing a dosage form with biphasic drug releas e characteristics. The inclusion of chitosan enhanced the properties of the films, rendering them stable at all physiological pH values. Pectin/HPMC f ilms were soluble at pH values above 3.0. All pectin/chitosan/HPMC films we re permeable to a model drug,: paracetamol. HPMC initially increased the pe rmeability of the films and subsequently reduced it at higher concentration s. The minimum permeability was obtained at pH 3 and at an HPMC level of 5% where the potential for polyelectrolyte complex formation between pectin a nd chitosan exists. The permeabilities of the films increased when they wer e exposed to pectinolytic enzymes, a system designed to mimic conditions in the colon. The film formulation thus show the potential for biphasic deliv ery with an initial, controllable slow phase that can be manipulated by cha nges in the formulation followed by a faster phase under conditions pertain ing in the colon. (C) 2001 Elsevier Science B.V. All rights reserved.