Novel Paradigms in Mucoadhesive Drug Delivery System

Mucoadhesion is a field of current interest in the design of drug delivery systems. Mucoadhesion is commonly defined as the adhesion between two materials, at least one of which is a mucosal surface. Mucoadhesive drug delivery system may be designed to enable prolonged residence time of the dosage form at the site of application or absorption and facilitate an intimate contact of the dosage form with the underline absorption surface. Extending the residence time of a dosage form at a particular site and controlling the release of drug from the dosage form are useful especially for achieving controlled plasma level of the drug as well as improving bioavailability. Application of these dosage forms to mucosal surfaces may be of benefit to drug molecules not amenable to the oral route, such as those that undergo acid degradation or extensive first-pass metabolism. The present review describes mucoadhesion, mucoadhesive polymers and use of these polymers in designing different types of mucoadhesive gastrointestinal, nasal, ocular, vaginal and rectal drug delivery systems. The research on mucoadhesives, however, is still in its early stage, and further advances need to be made for the successful translation of the concept into practical application in controlled drug delivery. INTRODUCTION: For the systemic delivery of drugs via various pharmaceutical product of different dosage form, the oral route drug delivery has been known as the most widely utilized route of administration among all other routes . Thus, oral controlled dosage forms have been developed for the past three decades, due to their considerable therapeutic advantages. However, this approach has not been suitable for those drugs which are absorbed only in a particular portion of gastrointestinal tract (GIT) or which are absorbed in various segment of the GIT to a different extent. Such drugs are characterized by a narrow absorption window due to the relatively short transit time of the gastrointestinal tract i.e. stomach and small intestine . Thus, after only a short period of less than 6 h, the CRDF has already left the upper gastrointestinal tract and the drug is released in nonabsorbing distal segments of the gastrointestinal tract. This results in a short absorption phase that is often accompanied by lesser bioavailability . Thus, the concept of mucosal adhesive or mucoadhesive was introduced in the early 1980s, into the field of control drug delivery. Mucoadhesive drug delivery system are those delivery systems which utilizes the assets of bioadhesion of certain water –soluble polymer which on hydration become adhesive, thus can be used for targeting a drug or drug delivery system in particular region of the body for the extended period of time, not only for local targeting of drug but also for the better control of