No abstract

Two types of poly(vinyl alcohol)-gel spheres were prepared with chitosan (CS/PVA-GS) and without chitosan (PVA-GS), and comparative studies were performed using these gel spheres (GSs). No change in particle size was observed by the addition of chitosan: nearly 45% of both particles were in the 5-10 microm range. In an in vivo gastrointestinal transit test, CS/PVA-GS prolonged the small-intestinal transit time more than PVA-GS. In an in vitro intestinal perfusion study, the mean transit time of these GSs was markedly reduced by pretreatment of the intestinal surface with a mucolytic agent, N-acetyl-L-cysteine, suggesting that the mucous layer on the intestinal surface plays an important role in controlling the transit rate of these GSs. The oral administration of aminophylline (theophylline) and ampicillin as model drugs incorporated in PVA-GS and CS/PVA-GS was examined in rats. While theophylline absorption from PVA-GS was not affected by the addition of chitosan, the improvement of ampicillin absorption by PVA-GS was enhanced by the chitosan combination.