AN INVESTIGATION OF THE RHEOLOGICAL BEHAVIOR OF THE MUCOADHESIVE MUCOSAL INTERFACE

One proposed mechanism of mucoadhesion involves the interpenetration of the mucus/mucoadhesive molecules, followed by the formation of non-covalent interactions. In this study, the effect of introducing a mucoadhesive macromolecule, the polyacrylic acid Carbopol 934P (paa), on the rheological behaviour of a mucus gel was evaluated using mechanical spectroscopy. It was found that a large increase in G' (the storage modulus) occurred in comparison to the values obtained when the mucus gel and the paa gel were evaluated separately at the same concentration. This gel strengthening was markedly affected by pH (i.e., it was minimal at pH values below 4.5 and above 8), while temperatures up to 45-degrees-C did not break down this gel. It was concluded that molecular interpenetration resulting in strengthening of the layer between the mucoadhesive/mucosal surface may offer an explanation for the large forces required to break a mucoadhesive joint.