Sustained-Release and Intragastric-Floating Granules of Indomethacin Using Chitosan in Rabbits

The release rate of indomethacin from chitosan granules was compared with that of conventional commercial indomethacin capsules and a sustained-release capsule. In contrast with the rapid release of a commercial conventional capsule form, sustained release from the chitosan granules was observed. Furthermore, the release rate could be controlled by changing the mixing ratio of drug and chitosan. The potential of chitosan granules as an oral sustained-release dosage form of indomethacin was investigated in rabbits. When a conventional commercial capsule was administered orally to rabbits, the plasma concentration reached the maximum level 1 h after administration. In the case of the granules with a 1: 2 mixture of drug and chitosan, the chitosan granules did not give a sharp peak of plasma concentration, but produced a sustained plateau level of indomethacin. The area under the plasma concentration curve (AUC)(0-8 h) value of chitosan granules showed a slightly higher value than that of commercial capsules. This may be due to the slow rate of release from the chitosan granules and the longer residence time in the stomach. Thus, in terms of decrease in the peak of plasma concentration and maintenance of indomethacin concentration in plasma, the chitosan granules were superior to the conventional commercial capsules. Indomethacin granule preparations using chitosan may be practically useful as oral preparations with reduced side effects and with prolonged action.