Cephradine-containing ethylcellulose microparticles (MPC) were prepared by the solvent evaporation method. Chitosan-coated MPC (Chi-MPC) were prepared by doping MPC with viscous chitosan solution and subsequently drying. When fluorescein isothiocyanate (FITC)-labeled chitosan-coated ethylcellulose microparticles without drug were administered intraduodenally, they moved slowly in the intestine, that is, most of them were retained at the upper and middle parts of the small intestine for more than 8 h, which is considered due to mucoadhesive properties of coated chitosan. When MPC and Chi-MPC was incubated at 37 degrees C in the JP 14 second fluid, pH 6.8, both released the drug slowly with similar release rates. Cephradine solution and suspension, MPC and Chi-MPC were administered intraduodenally to investigate intestinal drug absorption. Only Chi-MPC suppressed the initial plasma level and maintained the plasma concentration for a long time up to 24 h, suggesting Chi-MPC would be useful for prolonged intestinal absorption of cephradine.