EVALUATION OF POLY(VINYL ALCOHOL)-GEL SPHERES CONTAINING CHITOSAN AS DOSAGE FORM TO CONTROL GASTROINTESTINAL TRANSIT-TIME OF DRUGS

Two types of poly(vinyl alcohol)-gel spheres were prepared with chitos an (CS/PVA-GS) and without chitosan (PVA-GS), and comparative studies were performed using these gel spheres (GSs). No change in particle si ze was observed by the addition of chitosan: nearly 45% of both partic les were in the 5-10 mu m range. In an in vivo gastrointestinal transi t test, CS/PVA-GS prolonged the small-intestinal transit time more tha n PVA-GS. In an in vitro intestinal perfusion study, the mean transit time of these GSs was markedly reduced by pretreatment of the intestin al surface with a mucolytic agent, N-acetyl-L-cysteine, suggesting tha t the mucous layer on the intestinal surface plays an important role i n controlling the transit rate of these GSs. The oral administration o f aminophylline (theophylline) and ampicillin as model drugs incorpora ted in PVA-GS and CS/PVA-GS was examined in rats. While theophylline a bsorption from PVA-GS was not affected by the addition of chitosan, th e improvement of ampicillin absorption by PVA-GS was enhanced by the c hitosan combination.