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, sphincte r of Oddi, and gallbladder is mediated through the migrating myoelectr ic complex and the action Of motilin. Erythromycin, a motilin agonist, has recently been studied as a gastrointestinal and biliary prokineti c agent. We hypothesized that erythromycin would increase interdigesti ve duodenal and sphincter of Oddi motility in a dose-dependent manner. Methods. In 10 anesthetized prairie dogs we determined the motility r esponses of the duodenum, sphincter of Oddi, and gallbladder to erythr omycin infusion during a three-log dosing regimen and correlated activ ity with serum concentrations of the drug. Results. Erythromycin admin istered at 0.01 and 0.1 mg/kg had no effect on duodenal or sphincter m otility. At 1.0 and 10 mg/kg, duodenal motility index increased by 451 % +/- 114% and 1070% +/- 480%, respectively, when compared with baseli ne values, (p < 0.05). Sphincter of Oddi motility index increased by 1 22% +/- 38% and 323% +/- 9,9%, respectively, at these same doses of er ythromycin (p < 0.05). Gallbladder pressure did not change significant ly during erythromycin infusion. Erythromycin serum concentration at 1 .0 mg/kg was 1.0 +/- 0.7 mug/ml. Conclusions. These data suggest that erythromycin stimulates interdigestive motility of the duodenum and sp hincter of Oddi in a dose-dependent manner at otherwise subtherapeutic concentrations of the drug.