The formation and permeability of drugs across free pectin and chitosan films prepared by a spraying method.

This study has investigated the permeation of drugs through free films made of pectin and chitosan. The background for this study is the intended use of the films as coating material in a colon-specific drug delivery device. The factors that varied when making the films were the pectin source and grade of the pectin, degree of deacetylation of the chitosan and ratio between pectin and chitosan. The permeability of the model drug in 0.1 M HCl was low with an average drug release of 1.3 x 10(-3)%/cm. The films containing high content of chitosan showed exponential kinetics while the films containing high content of pectin showed 0-order kinetics. The release of drug in phosphate buffer pH 6.8 showed 0-order kinetics. The lowest permeability was obtained for a film consisting of a high content of pectin to chitosan, chitosan with a high degree of deacetylation and non-amidated low methoxylated citrus pectin. The permeation of paracetamol for this combination was 9.4 x 10(3)%/cm. This film combination had a combined diffusion of only 0.046%/cm after 1 h in 0.1 M HCl and 4 h in phosphate buffer pH 6.8.