ABSTRACT:
Per-oral drug administration is the traditional and most common method of drug administration but the drugs bioavailability is reduced as it is subjected to extensive pre-systemic degradation in the gut wall (or) liver. Parenteral route of drug administration achieves 100% bio-availability but due to poor patient acceptability and the risk of maintaining drug levels in the blood in cases of chronic medication makes it undesirable. The buccal region of the oral cavity is an attractive target for administration of the drug of choice, in overcoming deficiencies associated with the latter mode of administration. Problems such as high first-pass metabolism and drug degradation in the gastrointestinal environment can be circumvented by administering the drug via the buccal route. Mucoadhesion can be defined as a state in which two components, of which one is of biological origin, are held together for extended periods of time by the help of interfacial forces. Mucoadhesion is a complex phenomenon which involves wetting, adsorption and interpenetration of polymer chains. The concept of mucoadhesion in drug delivery was introduced in the early 1980s. This article aims at reviewing structure of oral mucosa, mechanism and theories of mucoadhesion, mucoadhesive polymers, dosage forms of mucoadhesive drug delivery system and their evaluation. .