Chitosan drugs

Ylitalo, R., Lehtinen, S., Wuolijoki, E., Ylitalo, P., and Lehtimaki, T. 2002. Cholesterol-lowering properties and safety of chitosan. Drug Res. 1, 1-7. 

Denkbas, E.B. Ottenbrite, R.M. 2006, Perspectives on chitosan drug delivery systems based on their geometries . Journal of Bioactive and Compatible Polymers, vol. 21, no. 4, pp. 351-368. 

Keywords Cancer therapy Chitosan Drug delivery Nanoparticles... 

Denkbas, E. B. Ottenbrite, R. M. (2006). Perspectives on chitosan drug deUveiy systems based on their geometries. J. Bioact. Compat. Polym., 21(4), 351-368. 

Boonsongrit, Y., Mitrevej, A Muelle, B. W Chitosan drug binding by ionic interaction, European J. 

Note that some treatment operations choose a pollution prevention technique to dispose of the float. This involves feeding the float to animals. When this is done for the situation where the feed animals are used for human consumption, organic compounds such as chitosan, carrageenan, lignosulfonic acid,or their derivatives can be used. Use only compounds that are approved by the Food and Drug Administration (FDA) Office of Veterinary Medicine. 

A number of articles considered the association of chitosan with polylactic acid or similar compounds [47-49] another group of articles presented new data on highly cationic chitosans [ 50 - 55]. More data have also been made available on the delivery of growth factors [56] and ophthalmic drugs [57,58], on the activation of the complement, macrophages [59-61] and fibroblasts [62], on mucoadhesion [63] and functionalization of chitin [64]. The development of new carriers for the delivery of drugs, and the interactions of chitosans with living tissues seem therefore to be major topics in the current research on chitosan. Therefore, this chapter will place emphasis on these aspects. 

A simple example of gel formation is provided by chitosan tripolyphosphate and chitosan polyphosphate gel beads the pH-responsive swelling abihty, drug-release characteristics, and morphology of the gel bead depend on polyelectrolyte complexation mechanism and the molecular weight. The chitosan beads gelled in pentasodium tripolyphosphate or polyphosphoric acid solution by ionotropic cross-hnking or interpolymer complexation, respectively. 

Ohya et al. reported poly(ethyleneglycol)-grafted chitosan nanoparticles as peptide drug carriers. The incorporation and release of insulin was dependent on the extent of the reaction of poly(ethyleneglycol) with chitosan [190]. 

A review of chitosan microspheres as carrier for drugs pubUshed recently by Sinha et al. provides insight into the exploitation of the various properties of chitosan to microencapsulate drugs. Various techniques used for preparing chitosan microspheres and evaluation protocols have also been reviewed, together with the factors that affect the entrapment efficiency and release ki-nefics of drugs [194]. 

Spray-drying of chitosan salt solutions provides chitosan microspheres having diameters close to 2-5 p.m and improved binding fimctionaUty. The chitosan microsphere free-flowing powder is compressible and hence most suitable as a drug carrier [ 195-204]. The following are some examples. 

By choosing the excipient type and concentration, and by varying the spray-drying parameters, control was achieved over the physical properties of the dry chitosan powders. The in vitro release of betamethasone showed a dose-dependent burst followed by a slower release phase that was proportional to the drug concentration in the range 14-44% w/w [200]. 

The nasal tissue is highly vascularized and provides efficient systemic absorption. Compared with oral or subcutaneous administration, nasal administration enhances bioavailability and improves safety and efficacy. Chitosan enhances the absorption of proteins and peptide drugs across nasal and intestinal epithelia. Gogev et al. demonstrated that the soluble formulation of glycol chitosan has potential usefulness as an intranasal adjuvant for recombinant viral vector vaccines in cattle [276]. 

The ability of chitosan hydrochloride to enhance the transcorneal permeability of the drug has been demonstrated [289]. Polyethylene oxide (PEO) was used as a base material to which ofloxacin-containing chitosan microspheres prepared by spray-drying were added and powder compressed resulting in circular inserts (6 mm). 

Co-administration of ofloxacin and chitosan in eyedrops increased the bioavailabUity of the antibiotic [290]. Trimethyl chitosan was more effective because of its solubility (plain chitosan precipitates at the pH of the tear fluid). On the other hand, N-carboxymethyl chitosan did not enhance the corneal permeability nevertheless it mediated zero-order ofloxacin absorption, leading to a time-constant effective antibiotic concentration [291]. Also W,0-carboxymethyl chitosan is suitable as an excipient in ophthalmic formulations to improve the retention and the bioavailability of drugs such as pilocarpine, timolol maleate, neomycin sulfate, and ephedrine. Most of the drugs are sensitive to pH, and the composition should have an acidic pH, to enhance stability of the drug. The delivery should be made through an anion exchange resin that adjusts the pH at around 7 [292]. Chitosan solutions do not lend themselves to thermal sterilization. A chitosan suspension, however. 

Ribeiro, A. J., Neufeld, R. Arnaud, P. Chaumeil, J. C. (1999). Microencapsulation of lipophilic drugs in chitosan-coated alginate microspheres. International Journal of Pharmaceutics, Vol. 187,1, (September 1999), pp. (115-123), ISSN 0378-5173 Rubinstein, A. (1995). Approaches and opportunities in colon-specific drug-delivery. Critical Reviews in Therapeutic Drug Carrier Systems, Vol 12, 2-3,1995), pp. (101-149), ISSN 0743-4863... 

Another polysaccharide system that has received considerable interest is the chitosans which are water soluble derivatives of chitin. These materials appear to be very biocompatible and degradable and so are potentially excellent candidates as polymeric drug systems (27). 

Borchard, G. LueBen, H.L. deBoer, A. G. Verhoef, J. C. Lehr, C.-M. Junginger, H.E., The potential of mucoadhesive polymers in enhancing intestinal peptide drug absorption. Ill Effects of chitosan-glutamate and carbomer on epithelial tight junctions in vitro, j. Control. Rel. 39, 131-138 (1996). 

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