Mucoadhesive properties of various pectins on gastrointestinal mucosa: an in vitro evaluation using texture analyzer.

Mucoadhesive performance of various pectins with different degrees of esterification and molecular weights was examined with porcine gastrointestinal (GI) mucosa, i.e. buccal, stomach, small intestine and large intestine, using a texture analyzer equipped with mucoadhesive platform. The instrumental parameters and test conditions such as pre-hydration time of pectin disc, contact time, contact force, test speed of probe withdrawal, GI tissue and test medium were also studied. Two parameters derived from texture analysis, namely maximum detachment force (F(max)) and work of adhesion (W(ad)), were used as parameters for comparison of mucoadhesive performance. The results indicated that degree of hydration of pectin disc affected the mucoadhesive properties. The mucoadhesion of pectin increased with the increased contact time and contact force, but not by the increased probe withdrawal speed. Tissue from different parts of GI tract and test medium also influenced the mucoadhesion. Pectins showed a stronger mucoadhesion on large intestinal mucosa than on small intestinal mucosa. The mucoadhesive properties of pectins on gastric mucosa depended on pH of the medium; a higher F(max) and W(ad) in a pH 4.8 medium than a pH 1.2 medium was revealed. Additionally, pectin showed a significantly higher mucoadhesion than carbomer934P in most of the GI mucosa tested. The results also demonstrated that the mucoadhesive performance of pectins largely depended on their characteristics, i.e. higher degree of esterification and molecular weight gave a stronger mucoadhesion. These findings suggest that pectin can be used as a mucoadhesive carrier for GI-mucoadhesive drug delivery systems.