Effects of Codeine on the Agitating Force and Gastrointestinal Transit Time in Dogs, for Use in Drug Absorption Studies

Drug absorption studies using dogs have been difficult because of different gastrointestina(GI) conditions between dogs and humans, including dogs' shorter intestinal transit time and strong agitation force in the GI tract. We attempted to modify the agitation force and GI transit time in dogs using codeine. The agitation force was examined based on the in vitro/in vivo correlation for a CR tablet of acetaminophen showing agitation-dependant release. Codeine improved the GI condition better than atropine or loperamide, employed previously.