Abstract: 
With progress in biotechnology, combinational chemistry and genomics, a broad variation of new, potent and specific therapeutics being formulated. But because of common problems like poor stability, high potency and low solubility of drugs the drug delivery can affect the efficacy and potency for commercialization. Thus there is a need to develop more effective, safe methods and devices for drug delivery. Among the various methods and devices that have been utilized for controlled delivery, microspheres are one of the most important and common type of drug delivery system. Microspheres represent a most important part of novel drug delivery system by integrity of their desired carrier capacity and small size. Because of their short residence time, bioadhesive properties can be linked to microspheres to produce mucoadhesive microspheres. Bioadhesion is a condition in which two materials, at least one of which is biological in nature and are carry together for extended period of time by means of interfacial forces. It is a carrier linked drug delivery system in which particle size if microspheres range from 1-1000 µm in diameter they having a core of drug and outer layers are completely of polymers as coating materials. Mucoadhesive microspheres show merits like improved bioavailability of drug because of more surface to volume ratio, efficient absorption, also they increase the intimate contact of drug with the mucus membrane, targets the drug at the specific absorption site as well as sustained and controlled delivery of drug from dosage form. The aim of the present study is to provide an overview of several features and aspects of mucoadhesive microspheres based on different methods of preparation, use of various polymers, methods of evaluation of mucoadhesive microspheres and their approaches in drug delivery.

Keywords:  Microspheres, Bioadhesion, Bioavailability, Polymers.