Response of the Human Gastrointestinal Tract to Erythromycin

Erythromycin has been shown to increase gastrointestinal motility in dogs when given in large doses, whereas small doses of the antibiotic elicit a premature migrating motor complex (MMC) in both dogs and humans. To study the effects of therapeutic doses of erythromycin in humans, erythromycin was given to 14 human volunteers either intravenously, 7 mg (kg · 30 min), or orally (500 mg) and pressure recordings were made from perfused or solid state catheters. Migrating motor complexes were counted before and after erythromycin administration. Intravenously administered erythromycin caused a large increase in the amplitude, duration, and frequency of gastric contractions whereas the small bowel appeared to be inhibited. No MMC was observed after the onset of the intravenous infusion. After oral administration of erythromycin the number of MMC increased significantly. Erythromycin caused side effects in 71% of subjects. In conclusion, at therapeutic doses erythromycin causes a disturbance of human upper gastrointestinal motility and can prove a useful tool in motility studies.