ABSTRACT
Peppas and Burin (1985) have considered the properties that are required for a mucoadhesive polymer. They state that the polymers should be of high molecular weight, should possess flexible chains, and should also possess hydrogen bonding groups (e.g. alcohols and carboxylic acids) and anionic groups. Park and Robinson (1984) have shown that mucoadhesive properties of poly (acrylic) acid hydrogels are lost on increasing the pH above the pKa of the polymer, indicating the importance of the ionisable groups. However, Park and Robinson (1984) also showed that the molecular mobility of the polymer was important, which implies that the mucoadhesive process involves some element of interpenetration of the polymer and mucous (see Section 8.2.2). Peppas and Burin (1985) state that the polymers should have surface properties such that spreading over the mucous layer is favourable. It has long been recognised that mucoadhesion, and indeed the other forms of bioadhesion can potentially be modelled in terms of interfacial properties of the mucous and the polymer.
