Lubiprostone is used for chronic idiopathic constipation and irritable bowel syndrome with constipation. Its mechanism is:

• A Activates chloride channel-2 (CIC-2) on apical brush border of enterocytes, secreting Cl– and water into gut lumen ✓
• B Activates guanylate cyclase-C (GC-C) receptors, raising cGMP and stimulating CFTR chloride secretion
• C Inhibits NHE3 (Na+/H+ exchanger 3), reducing colonic sodium absorption and increasing intraluminal water retention
• D Serotonin 5-HT4 agonist enhancing colonic motility and peristaltic reflexes

Explanation

Lubiprostone is a bicyclic fatty acid (prostaglandin E1 metabolite) that selectively activates type 2 chloride channel (ClC-2) on the apical membrane of intestinal epithelial cells. This opens the chloride channel, promoting secretion of chloride ions and secondarily water into the gut lumen, softening stool and increasing bowel movement frequency. Option B describes the mechanism of linaclotide (GC-C agonist, also a constipation drug); option D describes prucalopride (5-HT4 agonist).

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.