Polysaccharide microparticles for the oral administration of gentamicin were designed in order to obtain an increased drug absorption by means of microparticle transport across the intestinal epithelia. Alginate/chitosan microparticles with a size of ~2 mum were developed by spray-drying a water solution containing the drug complexed with the polyanionic alginate and subsequent alginate cross-linking process by calcium ions and chitosan. The pre-formulation study, performed by changing the concentration of both cross-linkers, led to the selection of the most suitable formulation which was assayed for its capacity to be translocated across intestinal epithelia, via both M cells contained in Follicle Associated Epithelium (FAE) of Peyer's patches and enterocytes of the mucosal epithelium. An ex vivo perfusion technique of rabbit and rat intestinal tissues containing Peyer's patches combined with an in vitro method by using Caco-2 cell monolayers demonstrated the microparticulate carrier ability to be taken up by both M cells and enterocytes. However, only the endocytosis by M cells appeared to provide the microparticle transport from the epithelium toward deeper sub-epithelial regions.
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