title: Preparation and in vitro evaluation of thiolated chitosan microparticles.
abstract: The objective of this study was to prepare a microparticulate drug delivery system being based on a new thiomer, namely a chitosan 2-iminothiolane conjugate (chitosan-TBA conjugate). Due to thiol groups being immobilized on chitosan, chitosan-TBA conjugate exhibits improved mucoadhesive and permeation enhancing properties. Because of these features microparticulate drug delivery systems based on chitosan-TBA conjugate might be a promising tool for the non-invasive administration of hydrophilic macromolecular drugs. Chitosan-TBA conjugate microspheres were prepared by the emulsification/solvent evaporation method. Fluorescein-isothiocyanate labelled dextran (FITC-dextran) was chosen as a model hydrophilic drug. Microspheres have been characterized by morphological analysis, thiol group content, swelling behaviour, polymer degradation drug load determination, dissolution test and mucoadhesion studies. Results reported in this work demonstrated the possibility to obtain stable microspheres without cross-linking agents. Thiolated chitosan microspheres seem to be more stable in aqueous media with respect to unmodified chitosan. The degradability by lysozyme appears quite similar for both polymers, showing that chemical modification does not influence the biodegradable properties of chitosan. Microspheres were able to control the drug release for at least 1 h, exhibiting comparatively strong mucoadhesive properties. The chitosan-TBA conjugate microparticles remain on the mucosa in a 2.5-fold higher concentration with respect to unmodified chitosan microparticles. These data suggest that chitosan-TBA conjugate microspheres have the potential to be used as a mucoadhesive drug delivery system.
authors.affiliation: Department of Pharmaceutical Chemistry, University of Pavia, Italy.
authors.forename: K
authors.initials: K
authors.lastname: Maculotti
authors.forename: I
authors.initials: I
authors.lastname: Genta
authors.forename: P
authors.initials: P
authors.lastname: Perugini
authors.forename: M
authors.initials: M
authors.lastname: Imam
authors.forename: A
authors.initials: A
authors.lastname: Bernkop-Schnürch
authors.forename: F
authors.initials: F
authors.lastname: Pavanetto
mesh_terms: D000268:Adhesiveness; D000818:Animals; D001672:Biocompatible Materials; D001673:Biodegradation, Environmental; D048271:Chitosan / Q000031:analogs & derivatives; D003692:Delayed-Action Preparations; D003911:Dextrans; D004339:Drug Compounding / Q000379:methods; D004355:Drug Stability; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D007413:Intestinal Mucosa / Q000502:physiology; D008855:Microscopy, Electron, Scanning / Q000379:methods; D008863:Microspheres; D009092:Mucous Membrane / Q000502:physiology; D009113:Muramidase; D013438:Sulfhydryl Compounds; D013499:Surface Properties; D013552:Swine
chemical_list: D001672:Biocompatible Materials; D003692:Delayed-Action Preparations; D003911:Dextrans; D005456:Fluorescent Dyes; D013438:Sulfhydryl Compounds; C510275:chitosan 2-iminothiolane; D048271:Chitosan; D009113:Muramidase; D016650:Fluorescein-5-isothiocyanate