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 micrograms/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.