الفهرس 
General IntroductionOnly 14 pages are availabe for public view
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Abstract
Summary:
Chitosan is a polysaccharide comprising copolymers of glucosamine and N-acetyl glucosamine and can be derived by partial deacetylation of chitin from crustacean shells; it is the second abundant natural polymer where it is naturally present in some microorganisms and fungi such as yeast. Chitosan has been investigated as an excipient in the pharmaceutical industry, to be used in direct tablet compression, as a tablet disintegrant, for the production of controlled release solid dosage forms or for the improvement of drug dissolution. Furthermore, chitosan has been used for production of controlled release implant systems for delivery of hormones over extended period of time. These properties, together with the very safe toxicity profiles, high biodegradability, biocompatibility, make chitosan an exciting and promising excipient for the pharmaceutical industry for the present and future applications.
Recently, an interpolymer complex (IPC) has attracted considerable interest by pharmaceutical researchers on account of its unique characteristics due to specific interaction between constituent polymers such as hydrogen bonds, electrostatic interaction, van der Waals force, or hyDROPhobic interactions, formation of an IPC between chitosan and anionic polymers might solve the problem of the pH dependency of anionic polymer because carboxyl groups, which are the main factors affecting the pH-dependent drug release.
On the other hand, hyDROPhilic gel-forming matrix tablets are widely used as oral extended-release dosage forms. Since the over all rate of drug release is regulated by the viscosity and the thickness of the gel layer formed from the matrix tablets.