Mosapride is an agonist of the serotonin (5-HT) receptor subtype 5-HT4 (Ki = 69.9 nM).{52440,30682} It is selective for 5-HT4 over 5-HT1, 5-HT2, dopamine D2, and a1- and a2-adrenergic receptors but acts as a partial antagonist at 5-HT3 (Ki = 1,189 nM).{52440,30682} It induces relaxation of precontracted rat esophageal thoracic muscularis mucosa preparations and enhances electrically evoked contractions in isolated guinea pig ileum (EC50s = 208.4 and 73.2 nM, respectively).{39019} Mosapride (0.5 and 1 mg/kg, i.v.) increases antral and duodenal, but not ileal or colonic, motility in conscious dogs.{52440} It also increases gastric emptying in rats when administered at doses ranging from 0.03 to 30 mg/kg.