Polymers and Permeation Enhancers: Specialized Components of Mucoadhesives

Mucoadhesive polymers have recently gained interest among pharmaceutical scientists as a means of improving drug delivery by promoting dosage form residence time and contact time with the mucous membranes. Mucoadhesion occurs between two surfaces, one of which is a mucous membrane and another is drug delivery system. Pharmaceutical aspects of mucoadhesion have been the subject of great interest during recent years because mucoadhesion could be a solution for bioavailability problems that result from a too short length of stay of the pharmaceutical dosage form at the absorption site within the gastro-intestinal tract. It has been a great challenge to the pharmaceutical sciences in order to enhance localised drug delivery or to deliver ‘difficult’ molecules (proteins and oligonucleotides) into the systemic circulation. Mucoadhesive systems remain in close contact with the absorption tissue, the mucous membrane, releasing the drug at the site of action leading to increase in bioavailability (both local and systemic effects). 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. The present review describes mucoadhesion, mucoadhesive polymers and use of these polymers in designing different types of mucoadhesive drug delivery systems.