Chitosan pharmaceutical applications

Dodane, V., and V.D. Vilivalam. 1998. Pharmaceutical applications of chitosan. Pharm Sci Technol Today 1 246. 

Another way to achieve desirable polymer properties is the modification of preformed polymers. This modification may take place on the reactive sites of the polymer chain through alkylation, hydrolysis, sulfonation, esterification, and other various reactions of polymers. Examples of natural polymers and their modifications are cellulose and its derivatives, chitin and chitosan, and polysaccharides. These are still to this day very important polymers for pharmaceutical applications. 

Sawayanagi et al. [301] reported the fluidity and compressibility of combined powders, viz., lactose/chitin, lactose/chitosan, potato starch/chitin, potato starch/chitosan as well as the disintegration properties of tablets made from these powders in comparison with those of combined powders of lactose/MCC and potato starch/MCC. This was done in order to develop direct compression dilutents as a part of their studies on pharmaceutical applications of chitin and chitosan. 

Most of the early biomedical and pharmaceutical application of chitosan-based systems dealt with topical applications and a few controlled drug... 

Dermal drug administration is yet another pharmaceutical application of chitosan. Topical all-frans-retinoic acid (ATRA) is an effective treatment for serious malignant melanoma. However, this topical retinoid incites skin irritation in the wide majority of patients, rendering it an ineffective treat-ment. As evidenced by the research of Cattaneo and Demierre, chitosan gels avail themselves to sustained, topical release of ATRA. These studies showed that manipulation of the viscosity or chitosan concentration of the gel enabled control of percutaneous penetration of the drug in mouse skin samples. In addition, their clinical trials on healthy hiunan subjects indicated minimal erythema occurrence from application of 0.1% ATRA in 1% and 3% chitosan gel. 

Chitosan (CS), a biomacromolecule obtained by deacetylating chitin, is used in many biomedical and pharmaceutical applications owing to its properties which include biodegradability, non-toxicity and antimicrobial activity. 

The chitosan and its derivatives show no acute toxicity and are not absorbed via transdermal route. The European pharmacopoeia contains a single monograph on chitosan hydrochloride. In the United States, chitosan is currently being included in the US Pharmacopoeia [Sarmento and das Neves, 2012]. The chitosan and its derivatives are deemed safe for use as permeation enhancer for transmucosal delivery of hydrophilic drugs and offer promising prospects for novel pharmaceutical applications [Junginger and Verhoef, 1998]. Despite the chitosan and its derivatives interact with lipids and proteins of the membranes of stratum corneum, they may not penetrate into deeper layers of the skin. This can be inferred from the absence of skin irritation by chitosan and its derivatives in Draize test [Aoyagi et al., 1991]. 

Casettari, L., Vllasaliu, D., Castagnino, E., Stolnik, S., Howdle, S., Ilium, L. (2012). PEGylated chitosan derivatives Synthesis, characterizations and pharmaceutical applications, 37(5), 659-685. 

Natural polymers have also been used as thermo-sensitive hydrogels, either on their own or in combination with other synthetic polymers. Popular natural polymers include chitosan, cellulose derivatives, dextran, xyloglucan and gelatin (Klouda and Mikos 2008). Chitosan is a polysaccharide derived from the shells of crustaceans and is produced by deacetylation of chitin, basically through the removal of the acetyl group using a concentrated NaOH solution (Fig. 11.5). The main advantage of chitosan for medical and pharmaceutical applications is its biocompatibility and inertness when in contact with human cells (Kumar et al. 

In this chapter, the main characteristics of chitin and chitosan and the more convenient techniques used for their characterization will be presented together with their main physical properties. Furthermore, the materials obtained with these polysaccharides will be described. It is important to recall that chitin is a natural polymer that is also biocompatible and biodegradable, an important advantage for biomedical and pharmaceutical applications. Good film forming properties is valuable for packaging or other applications in the domain of materials. 

In the paragraph above, we have discussed hydrogels of chitosan and cationic hybrid gels, based on chitosan, with potential for biomedical applications. However, there are also other cationic hydrogels that can be useful for medical and pharmaceutical applications. Jia et al. designed a... 

Hejazi R., Amiji M., Chitosan-based delivery systems Physicochemical properties and pharmaceutical applications, in Polymeric Biomaterials, Ed. Dumitriu S., 2nd Edition, Marcel Decker, Inc., New York, 2002, pp. 213-237. 

---