Erythromycin accelerates gastric emptying in patients with diabetic gastroparesis. Its prokinetic action results from agonism at which receptor?
- A Dopamine D2 receptor in the chemoreceptor trigger zone
- B 5-HT4 receptor on enteric cholinergic neurons
- C Motilin receptor on gastric smooth muscle ✓
- D Gastrin CCK-B receptor on parietal cells
Correct answer: C. Motilin receptor on gastric smooth muscle
Explanation
Erythromycin is structurally similar to motilin and binds motilin receptors on gastric antral smooth muscle, mimicking the fasting hormone that initiates the migrating motor complex and thereby triggering strong antral contractions and fundic relaxation. Metoclopramide and cisapride act on dopamine D2 and 5-HT4 receptors respectively, which distinguishes their mechanism from erythromycin. Gastrin receptors are not targeted by any prokinetic agent.
Reference: Katzung Basic and Clinical Pharmacology, 16th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.