Mucoadhesion and drug permeability of free mixed films of pectin and chitosan: An in vitro and ex vivo study

The objective of this study was to identify the important factors for the drug permeability and mucoadhesion of casted free pectin/chitosan combination films. The factors varied were: the type of pectin (low and high methoxyl pectin) and the ratio pectin:chitosan (25:75, 50:50 and 75:25). the model drug used for measuring drug permeability was paracetamol. A texture analyzer was used for measuring mucoadhesion by using two different setups: (1) in vitro tensile tests measuring the detachment force of films versus a mucin dispersion and (2) ex vivo shear tests measuring the friction forces between pre-hydrated films and fresh porcine small intestine, with the system immersed in phosphate buffer, pH 6.8. The type of pectin used in the combination films did not have a significant effect on the drug permeability. The ex vivo mucoadhesion test revealed significant differences between low and high methoxyl pectin only for the 50:50 pectin:chitosan films. For that type of film, the peak and friction forces were highest for high methoxyl pectin. Both the mucoadhesion and drug permeability generally increased with decreasing amounts of pectin relative to chitosan in the films. (C) 2008 Elsevier B.V. All rights reserved.