Cross linking agents

Microspheres are characteristically spherical and free flowing powders having particle size ranging from 1-1000 μm consisting of proteins or synthetic polymers. Microspheres are free flowing solid particle made up of biodegradable and non-biodegradable components Microspheric drug delivery system has wide range of application as it covers targeting the drug to particular site to imaging and helping the diagnostic features. Microspheres form an essential part of novel drug delivery systems. Microspheres reduce the dosing frequency and improve patient compliance by designing and evaluating Sustained Release microspheres for effective control of many chronic diseases. A well designed controlled drug delivery system can overcome some of the problems of conventional therapy and enhance the therapeutic efficacy of a given drug. There are various approaches in delivering a therapeutic substance to the target site in a sustained controlled release fashion. A Microsphere has its drug dispersed throughout the particle i.e. the internal structure is a matrix of drug and polymeric excipients. The objective of this article is to emphasize on the principles underlying the development and evaluation of microspheres as a controlled and targeted drug delivery system.