Many drugs have the problem such as poor stability, water insolubility, side effects, toxicity. The administered dosage has not properly reached their target because it is distributed throughout the rest of the body in accordance with its physicochemical and biological properties. So many researcher are searching the good drug carrier. Nanoparticles are solid colloidal particles with diameters ranging from 1- 1000nm.They consist of drug carriers in which the active ingredient is dissolved, dispersed, entrapped, encapsulated, adsorbed or chemically attached .
Chitosan is one of the most commonly used natural polymers in the production of nanomedicines, because it displays very attractive characteristics for drug delivery and has proved very effective when formulated in a nanoparticulate form. Ohya and coworkers (1994) first described the chitosan nanoparticles in carry and to intravenous delivery of 5-fluorouracil, an anticancer drug. Chitosan posses some ideal properties of polymeric carriers for nanoparticles such as biocompatible, biodegradable, nontoxic and inexpensive. Furthermore it posses positively charge and exhibits absorption enhancing effect. These properties render chitosan a very attractive material as a drug delivery carrier The chitosan nanoparticles has greater advantage as drug carrier due to its slow or controlled drug release, has the potential to improve solubility and stability of drug and reduced toxicity. The amino and carboxyl group in chitosan form adhesive effect by combines with glycoprotein in mucus as well as the interaction between the chitosan and mucoprotein in mucus serves increased retention time of drugs, continuous drug flow and also the bioavailability of drugs. The biodegradability and safetyof drug carrier is very much important. The US Food and Drug administration has certified chitosan to be used in wound dreesing.