Chitosan and its Derivatives

Numerous chemical modification like quatemization [117], deoxycholic acid modification [118], galactosylation [119], PEI grafting [120], and thiolation [121] have been carried out by various groups in an attempt to improve transfection efficiency. 

Chemical modification is a powerful tool for controlling the interaction between polymer and drug and thus for enhancing the loading capacity and controlling drug release from the matrix. Modified chitosan improves the bulk properties for the sustained release and has a wide range of pharmaceutical applications. 

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Thanou M, Verhoef JC, and Junginger HE (2001) Chitosan and its derivatives as intestinal absorption enhancers. Adv. Drug Deliv.Rev. 50 S91-S101. 

Thanou M, Verhoef JC, Junginger HE (2001) Oral drug absorption enhancement by chitosan and its derivatives. Adv Drug Del Rev 52 117-126... 

The mucoadhesive properties of several classes of hydrogels have been identified, and two types of polymers have attracted special attention. Polyacrylates and their cross-linked modifications represent the anionic type, chitosan and its derivatives the cationic group. In addition, both types of polymers show a number of interesting characteristics beneficial for the administration of a wide range of therapeutics. 

As was made clear earlier, chitosan and its derivatives are of more value than chitin. Currently the chitin is deacetylated by a harsh alkali treatment. If they... 

Because it has a variety of biological activities such as antioxidant, antimicrobial, anti-inflammatory, anticancer, and immune-stimulating effects, chitosan offers a number of uses in food, cosmetic, biomedical, and pharmaceutical industries. In this section, the nutraceutical properties of chitosan and its derivatives are discussed. 

Many studies have been conducted on the antimicrobial activity of chitosan since Allan and Hadwiger (1979) first reported that chitosan and its derivatives had broad-spectrum antimicrobial effects. The group of researches proved that chitosans are capable of inhibiting the growth of some microorganisms including bacteria, yeasts, and fungi. 

O Improvement of Oral Drug Absorption by Chitosan and Its Derivatives... 

Chitosan and its derivatives are the most widely used cationic polymeric excipients. Chitosan consists of (31—>4 D-glucosamine units and is derived by the deacetylation of chitin from insects, crustaceans and fungi. It interacts ionically with the anionic substructures of sialic acid residues on the mucus layer. Chitosans are rapidly hydrated in a low pH environment like the gastric fluid and do not swell above pH levels of 6.5, exhibiting no more mucoadhesion. 

Chitosan and its derivatives have been applied to enhance the absorption of proteins (e.g., insulin) and polypeptides (e.g., buserelin). /V-Trimethyl chitosan chloride exhibits opening of the tight junctions of the intranasal and intestinal epithelial cells so that the transport of hydrophilic compounds is increased through the para-cellular transport pathway. The absorption-enhancing effect was concentration dependent and reversible and dependent on the integrity of the intercellular cell contact zone. 

Bernkop-Schnurch, A. (2000), Chitosan and its derivatives Potential excipients for peroral peptide delivery systems, Int. J. Pharm., 194(1), 1-13. 

The capacity to preconcentrate anions has enabled the use of chitosan and its derivatives in modified electrodes, for application in sensor and biosensor electrochemistry [233]. To facilitate improving water solubility of biologically useful chitosan derivatives, N-methylene phosphonic chitosan has been prepared using a one-step reaction that allowed homogeneous modifications [234]. 

Park JH, Saravanakumar G et al (2010) Targeted delivery of low molecular drugs using chitosan and its derivatives. Adv Drug Deliv Rev 62 28 1... 

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