Erythromycin commonly causes abdominal cramping, nausea and diarrhea even at standard doses. The mechanism responsible for these gastrointestinal effects is:
- A Stimulation of motilin receptors triggering premature migrating motor complexes ✓
- B Alteration of gut flora with overgrowth of Clostridioides difficile
- C Direct mucosal irritation of the gastric epithelium
- D Inhibition of intestinal cytochrome P450 enzymes
Correct answer: A. Stimulation of motilin receptors triggering premature migrating motor complexes
Explanation
Erythromycin is a motilin receptor agonist. By mimicking motilin it induces premature migrating motor complexes in the proximal gut, causing cramping, nausea and diarrhea. This same property underlies its off-label use as a prokinetic agent in gastroparesis. Macrolides also inhibit CYP3C4, which causes important drug interactions, but that does not explain the gastrointestinal symptoms. Clostridioides difficile colitis is classically linked to clindamycin and broad-spectrum agents.
Reference: Katzung Basic and Clinical Pharmacology, 16th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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