Ex vivo mucoadhesion of different zinc-pectinate hydrogel beads.

The objective of this study was to investigate the mucoadhesive properties of pre-swelled hydrogel beads made of six types of pectin from three manufacturers. The types of pectin differed mainly in the degree of methoxylation and degree of amidation. Zinc ions were used as cross-linking agent. The mucoadhesive properties were tested on an inverted fresh porcine small intestine attached to a rotating cylinder. Beads made of pectin with a high degree of methoxylation (70%) showed superior mucoadhesive results compared to the other formulations, which could be correlated to the lower amount of zinc in this formulation, subsequently leading to a lower amount of cross-linking and higher mobility of the polymer chains of these beads. This study therefore also indicated the importance of doing mucoadhesive measurements on relevant formulations, and not basing the understanding solely on investigating polymer solutions. Samples from different manufacturers produced the same results.