Abstract
Chitosan/cellulose acetate multimicrospheres (CCAM) with or without ranitidine (RT) were prepared by the method of W/O/W emulsion with no toxic reagents and had the size interval of 200–280 μm. The angles of repose were only a little more than 30° and the maximum angles of one‐plane‐critical‐stability (OPCS φ) were about 20°. The CCAM had good suspension ability for the tapped density of CCAM was less than 0.127g/mL. The pH value affected the swelling ability of CCAM and the relative humidity had little effect on the characteristics of CCAM when it was not more than 75%. The CCAM system had good effect on the controlled release of RT in vitro and the release rate was almost 60% during 48 h. Furthermore the release of RT was not affected by pH value of release medium. The mucoadhesive tests showed that CCAM could retain in gastrointestinal tract for an extended period of time. There were 53.7% of CCAM remained in stomach after administered for 2½ h and 98.9% of CCAM remained in stomach and small intestine after administered for 3½ h. These results suggest that CCAM is a useful dosage form targeting the gastric mucosa or prolonging gastric residence time as a multiple‐unit mucoadhesive system. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007