Background: In earlier studies, erythromycin stimulated but octreotide inhibited gastric antral contractions, as each drug induced phase 3-like episodes.
Methods: To assess the effect of erythromycin pretreatment on octreotide-induced changes in antroduodenal motility, 16 patients were studied (mean age, 8.7 +/- 1.5 years, 8 male): 6 with severe gastroesophageal reflux, 4 with cyclic vomiting, 3 with gastroparesis, 2 with chronic intestinal pseudo-obstruction, and 1 with Crohn's disease and unexplained nausea and vomiting. After recording fasting antroduodenal motility for 3 hours, 1 mg/kg intravenous erythromycin was administered over 30 minutes. Sixty minutes after the erythromycin infusion, 0.5 microg/kg subcutaneous octreotide was administered, followed 1 hour later by a meal.
Results: Phase 3 occurred spontaneously in 10 patients and after erythromycin in 12 patients. When administered after erythromycin, octreotide immediately induced phase 3s contractions in 15 patients, beginning in the antrum. In 7 children, some of the octreotide-induced phase 3s did not propagate. After the meal, antral contractions continued in all patients. The fed pattern was replaced in 14 patients by alternating phase 3 and phase 1 activities.
Conclusions: Pretreatment with erythromycin prevented octreotide-induced inhibition of antral contractions. Inhibition of antral contractions by octreotide may be mediated through either a direct or indirect suppression of motilin release, because antral contractions persist after pretreatment with the motilin receptor agonist erythromycin.