Q: How Erythromicin works as a motility agent?

Answer: Erythromycin, the macrolide antibiotic, daily divided dose of 1-2g daily is one of the drug of choice as a gastrokinetic agent in ICUs.  Erythromycin acts as a motilin agonist through its interaction with motilin receptors found in the stomach and upper GI tract. Erythromycin accelerates gastric emptying by increasing the frequency and amplitude of stomach and duodenal contractions.

Reference:

Stevens JE, Jones KL et al. Pathophysiology and pharmacotherapy of gastroparesis: current and future. perspectives. Expert Opin Pharmacother 2013; 14 (9): 1171-86