Erythromycin markedly accelerates gastric emptying, possibly because it acts as a
motilin agonist. In the present study, the effect of an equipotent dose of
motilin was tested. In six patients with severe diabetic
gastroparesis, gastric emptying of liquids and solids was examined scintigraphically after
motilin or placebo in a double-blind crossover study.
Motilin (10 pmol.kg-1.min-1) or saline was infused over a 90-minute period starting 5 minutes before breakfast.
Motilin markedly accelerated emptying. For liquids, the half-emptying time was reduced from 51 +/- 6 to 22 +/- 11 minutes (P less than 0.01) and for solids from 111 +/- 4 to 51 +/- 12 minutes (P less than 0.01). The mean increase in plasma
motilin levels was 1315 +/- 342 pg/mL, corresponding to an effective infusion rate of about 4 pmol.kg-1.min-1. In the control experiments, basal
motilin levels (173 +/- 17 pg/mL) were within the normal range but increased steadily postprandially, reaching 321 +/- 25 pg/mL at the end of the study period, probably reflecting gastric distension. The postprandial increase in
pancreatic polypeptide level was blunted compared with accepted normal values but was more pronounced during
motilin infusion, i.e., 650 +/- 217 vs. 279 +/- 66 pg/mL (P less than 0.01), probably because of the improved emptying. Our data show that
motilin accelerates gastric emptying in diabetic
gastroparesis and support the hypothesis that
erythromycin's effect is mediated through
motilin receptors.