Bioadhesive polymers: novel tool for drug delivery.

Mucoadhesive drug delivery systems came into picture in the early 1980s and are one of the most studied novel delivery systems. Several researchers have focused on the investigations of the interfacial phenomena of mucoadhesion with the mucus. Mucoadhesion can be defined as a state in which two components, of which one is of biological origin, are held together for an extended period of time by the help of interfacial forces. A number of polymers have shown characteristics of bioadhesion and have been used in the formulation of various conventional and novel drug delivery systems. Studies demonstrated that these carriers not only increase the local therapeutic activity, but also increase the systemic availability of the drugs by increasing the residence time at the site of application. The current review is an attempt to throw some light on the basics of the mucoadhesion: the mechanism of bioadhesion and the polymers that are used in the design of the bioadhesive delivery system with their properties that affect the bioadhesion.