Mucoadhesion can be defined as adhesion in biological setting. Process of mucoadhesion
takes place in 3 stages- the first stage being that of wetting or swelling of mucoadhesive polymer. Second
stage involves interpenetration of the chains of mucoadhesive polymer and the third stage involves
formation of chemical bonds between entangled chains. Several polymer related factors like molecular
weight, chain length, degree of cross-linking, hydration, functional groups, charge, polymer concentration
and several environmental and physiological factors like contact time, mucin turnover rate and
mucus viscosity affect the degree of mucoadhesion. Formulation scientists have structured and engineered
several mucoadhesive polymers for their usefulness in enhancement of bioavailability, controlled
and targeted drug delivery. Mucoadhesive polymers can be classified as non-specific first generation polymers and
novel second generation polymers based on the mechanism of mucoadhesion. Mucoadhesive drug delivery systems have
been applied to buccal cavity, oesophagus, gastrointestinal tract, eye, nasal cavity, vagina and rectal cavity. Several in
vitro/ex vivo and in vivo evaluation techniques have evolved for the evaluation of mucoadhesive strength of these polymers.
This review provides historical perspective on mucoadhesive polymers and an understanding of the phenomenon of
mucoadhesion, factors affecting mucoadhesion, types of mucoadhesive polymers, their practical applications and the various
evaluation techniques for determination of mucoadhesive strength.