The effect of erythromycin on motility of the duodenum, sphincter of Oddi, and gallbladder in the prairie dog

Background. Interdigestive motility of the stomach, duodenum, sphincter of Oddi, and gallbladder is mediated through the migrating myoelectric complex and the action of motilin. Erythromycin, a motilin agonist, has recently been studied as a gastrointestinal and biliary prokinetic agent. We hypothesized that erythromycin would increase interdigestive duodenal and sphincter of Oddi motility in a dose-dependent manner. Methods. In 10 anesthetized prairie dogs we determined the motility responses of the duodenum, sphincter of Oddi, and gallbladder to erythromycin infusion during a three-log dosing regimen and correlated activity with serum concentrations of the drug. Results. Erythromycin administered at 0.01 and 0.1 mg/kg had no effect on duodenal or sphincter motility. At 1.0 and 10 mg/kg, duodenal motility index increased by 451% ± 114% and 1070% ± 480%, respectively, when compared with baseline values, (p < 0.05). Sphincter of Oddi motility index increased by 122% ± 38% and 323% ± 99%, respectively, at these same doses of erythromycin (p < 0.05). Gallbladder pressure did not change significantly during erythromycin infusion. Erythromycin serum concentration at 1.0 mg/kg was 1.0 ±0.7 μg/ml. Conclusions. These data suggest that erythromycin stimulates interdigestive motility of the duodenum and sphincter of Oddi in a dose-dependent manner at otherwise subtherapeutic concentrations of the drug.