Mucoadhesives in the gastrointestinal tract: revisiting the literature for novel applications.

This article investigates applying mucoadhesives to manipulate friction and to achieve locomotion of an alternative colonoscopic device through the large intestine. Considering that such an application of mucoadhesives is new, the authors recognised the need to revisit the different aspects of mucoadhesion in the gastrointestinal tract on the basis of the literature and to re-evaluate them according to the requirements for intestinal locomotion. First, the material properties, which are critical for the locomotion mechanism and specific categories of mucoadhesives characterised by those critical properties were identified. The next step was to examine the structural characteristics of those categories to specify which of the already synthesised mucoadhesives are promising candidates for friction manipulation. Then, the response of those mucoadhesives to a number of environmental stimuli was examined. At the end, two in vitro experiments were carried out to study the potential of mucoadhesives for intestinal locomotion. A comparative analysis of the role of mucoadhesives in drug delivery and in intestinal locomotion leads to the conclusion that the two applications can be approached to one extent with common principles, but crucial differences are present as well.