Erythromycin commonly causes abdominal cramps, nausea and diarrhea even at therapeutic doses. The pharmacological basis of these gastrointestinal adverse effects is:

• A Direct mucosal ulceration of the gastric epithelium
• B Cholinergic stimulation through muscarinic receptor activation
• C Inhibition of human mitochondrial protein synthesis in enterocytes
• D Agonist action at motilin receptors stimulating gastrointestinal motility ✓

Explanation

Erythromycin is a motilin receptor agonist and stimulates migrating motor complexes, increasing gastric and intestinal motility, which produces cramping and diarrhea. This same property is exploited therapeutically at low doses as a prokinetic agent in gastroparesis. It is not anticholinergic, it does not inhibit human mitochondrial ribosomes at these concentrations, and the effect occurs even with enteric-coated formulations, ruling out simple mucosal irritation.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.