Chitosan as absorption enhancer

Schipper, N.G.M., et al. 1999. Chitosans as absorption enhancers of poorly absorbable drugs 3 Influence of mucus on absorption enhancement. Eur J Pharm Sci 8 335. 

Schipper, N. G., Olsson, S., Hoogstraate, J. A., et al. Chitosans as absorption enhancers for poorly absorbable drugs 2. Mechanism of absorption enhancement. Pharm. Res. 14 923-929, 1997. 

A-Trimethyl Chitosan as Absorption Enhancer of Peptide Drugs. Ill... 

Schipper NG, Olsson S, Hoogstraate JA, de Boer AG, Varum KM, Artursson P (1997) Chitosans as absorption enhancers for poorly adsorbable drugs 2 Mechanism of absorption enhancement Pharm Res 14 923-929... 

Schipper N G M, Olsson S, Hoogstraate J A, et al. (1997). Chitosans as Absorption Enhancers for Poorly Absorbable Drugs 2 Mechanism of Absorption Enhancement. Pharm. Res. 14 923-929. 

Schipper N G, Varum K M, Artursson P (1996). Chitosans as absorption enhancers for poorly absorbable drugs. 1 Influence of molecular weight and degree of acetylation on drug transport across human intestinal epithelial (Caco-2) cells. Pharm. Res. 13 1686-1692. 

Thanou, M. (2000) Chitosan Derivatives in Drug Delivery. Trimethylated and Carboxy-methylated Chitosan as Safe Enhancers for the Intestinal Absorption of Hydrophilic Drugs, PhD Thesis, Leiden University, Leiden, pp. 91-108. 

Van der Merwe, Verhoef, J.C., Kotze, A.F. and Junginger, H.E. (2004b) A-Trimethyl chitosan chloride as absorption enhancer in oral peptide drug delivery. Development and characterization of minitablet and granule formulations. Eur. J. Pharm. Biopharm. 57 85-91. 

Hamman et al. [281,282] tested five trimethyl chitosans with different degrees of quaternization as nasal delivery systems the degree of quaternization had a major role in the absorption enhancement of this polymer across the nasal epithelia in a neutral environment. 

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. 

Tengamnuay P, Sahamethapat A, Sailasuta A, Mitra AK (2000) Chitosans as nasal absorption enhancers of peptides comparison between free amine chitosans and soluble salts. Int J Pharm 197 53-67. 

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

Ilium et al. [49] evaluated chitosan solutions as delivery platforms for nasal administration of insulin to rats and sheep. They reported a concentration-dependent absorption-enhancing effect with minimal histological changes of the nasal mucosa in all concentrations applied. 

Chitosan not only displays mucoadhesive properties, but also acts as an absorption enhancer in the intestinal cell layer membrane [34,35]. The mucoadhesion raises the concentration of... 

Therefore, the enhancement of transport is not accompanied by damage to the cells, which is superior to the absorption-enhancing effects of other small molecules, which lead to irreversible changes in the cell membrane and damage to the cell. Thus, much attention has been paid to chitosan as a polymeric substance that enhances GI absorption. 

Aspden, T.J., L. Ilium, and O. Skaugrud. 1996. Chitosan as a nasal delivery system Evaluation of insulin absorption enhancement and effect on nasal membrane integrity using rat models. Eur J Pharm Sci 4 23. 

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