Biodegradability of Chitosan Fibres

Struszczyk, H.; Wawro, Dariusz; Niekraszewicz, Antoni

doi:10.1007/978-94-011-5942-5_66

Cited by 21 publications

(16 citation statements)

References 5 publications

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“…Chitosan is a hydrophilic cationic copolymer produced by the deacetylation of chitin and composed of glucosamine and acetyl glucosamine units (31); it is a biodegradable, biocompatible, and mucoadhesive biopolymer (32)(33)(34)(35)(36)(37). Endothermically gelling chitosan solution is prepared by supplementing an aqueous solution of chitosan with β-glycerophosphate (β-GP) salt, an additive that plays three essential roles: (1) to increase the pH into physiological range of 7.0-7.4; (2) to prevent immediate precipitation or gelatin, and (3) to allow for controlled hydrogel formation when an increase in temperature is imposed (38,39).…”

Section: Introductionmentioning

confidence: 99%

Preparation and Evaluation of Thermosensitive Liposomal Hydrogel for Enhanced Transcorneal Permeation of Ofloxacin

Hosny

2009

AAPS PharmSciTech

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Abstract. Ofloxacin, available as ophthalmic solution, has two major problems: first, it needs frequent administration every 4 hours or even every 1 hour to treat severe eye infection; second, there is formation of white crystalline deposit on cornea due to its pH-dependent solubility, which is very low at pH of corneal fluid. In order to provide a solution to previous problems, ofloxacin in this study is prepared as topically effective in situ thermosensitive prolonged release liposomal hydrogel. Two preparation procedures were carried out, leading to the formation of multilamellar vesicles (MLVs) and reverse-phase evaporation vesicles (REVs) at pH 7.4. Effects of method of preparation, lipid content, and charge inducers on encapsulation efficiency were studied. For the preparation of in situ thermosensitive hydrogel, chitosan/β-glycerophosphate system was synthesized and used as carrier for ofloxacin liposomes. The effect of addition of liposomes on gelation temperature, gelation time, and rheological behaviors of the hydrogel were evaluated. In vitro transcorneal permeation was also determined. MLVs entrapped greater amount of ofloxacin than REVs liposomes at pH 7.4; drug loading was increased by including charge-inducing agent and by increasing cholesterol content until a certain limit. The gelation time was decreased by the addition of liposomes into the hydrogel. The prepared liposomal hydrogel enhances the transcorneal permeation sevenfold more than the aqueous solution. These results suggested that the in situ thermosensitive ofloxacin liposomal hydrogel ensures steady and prolonged transcorneal permeation, which improves the ocular bioavailability, minimizes the need for frequent administration, and decreases the ocular side effect of ofloxacin.

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Section: Introductionmentioning

confidence: 99%

Preparation and Evaluation of Thermosensitive Liposomal Hydrogel for Enhanced Transcorneal Permeation of Ofloxacin

Hosny

2009

AAPS PharmSciTech

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“…4 From a chemical point of view, these modifications were done to make them soluble in water or organic solvents 5 and to improve their natural metal chelating properties. 6 Regarding their biological activity, the main objectives were to improve their fungicidal 7 and bactericidal 8 properties. Carbamates are widely used in agriculture because of their known insecticide, fungicide, and herbicide activity.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of chitosan alkyl carbamates

Cárdenas

Paredes

Cabrera‐Barjas

et al. 2002

J of Applied Polymer Sci

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ABSTRACT:The synthesis of chitosan methylcarbamate (ChMC) and ethylcarbamate (ChEC) is described by using a new methodology. Polymers with substitution degrees up to 63% for ChEC and 68.5% for ChMC were obtained. Derivatives with lower substitutions were acid soluble but those with higher ones were completely insoluble. This could be due to the loss in hydrophilic sites when the substitution degree increases. The reaction conditions and degree of substitution obtained for both derivatives were also described. A complete chemical characterization was carried out by spectroscopic techniques. The thermal degradation of chitosan and derivatives were studied in the range 25-500°C and both derivatives were shown to be thermally less stable than chitosan.

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“…Among all the hydrogels, chitosan has attracted a lot of attention in the pharmaceutical and medical fields because it has favorable biological properties such as biodegradability [17] and biocompatibility [18,19]. Chitosan, a deacetylated derivative of chitin, is a naturally occurring polysaccharide found abundantly in marine crustaceans, insects and fungi.…”

Section: Introductionmentioning

confidence: 99%

Chitosan Beads as a New Gastroretentive System of Verapamil

2006

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The main objective of this project is to design a new extended release gastroretentive mutiparticulate delivery system for verapamil (VP) by incorporation into hydrogel beads made of chitosan. The beads were formed by dropping solutions of VP and chitosan in a solution of tripolyphosphate using a syringe pump with adjustable constant rate. The formed beads were then further crosslinked using glutraldehyde and the excess glutraldehyde were then washed. The physical properties of the prepared beads such as beads sizes, shapes, friabilities and loading efficiencies were determined. The floating characteristics and the release profiles were also studied. The produced beads from all batches showed a very good spherical geometry with mean diameter in the range of 1.3 -2.0 mm. The drug loading efficiency was around 42% for all batches. The % friabilities were less than 1% indicating that the beads surfaces are highly resistant to attrition. Batches B 3 and B 4 (prepared using medium molecular weight chitosan) showed both the slowest release rate among all the prepared batches and showed good floating characteristics comprising short onset (around 5 minutes) and the long duration of buoyancy (more than 6 hours). All the batches exhibited a kinetic model of combined mechanism of diffusion partially through a swollen matrix and partially through water-filled pores. The preparation of chitosan beads using this technique would provide a simple and commercially viable method of preparation of chitosan beads for controlling the release of some drugs.

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Biodegradability of Chitosan Fibres

Cited by 21 publications

References 5 publications

Preparation and Evaluation of Thermosensitive Liposomal Hydrogel for Enhanced Transcorneal Permeation of Ofloxacin

Preparation and Evaluation of Thermosensitive Liposomal Hydrogel for Enhanced Transcorneal Permeation of Ofloxacin

Synthesis and characterization of chitosan alkyl carbamates

Chitosan Beads as a New Gastroretentive System of Verapamil

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