CH 84 IBS/IBD & Other GI Drugs

Question 1

Drug: Alosetron (Lotronex)

Answer 1

Class: 5-HT₃ antagonist (IBS-D specific agent)
MOA: Blocks serotonin receptors in GI tract, reducing motility and pain.
Note: Only approved for severe IBS-D in women; risk of serious GI toxicity.

Question 2

Drug: lubiprostone (Amitiza)

Answer 2

Class: chloride channel activator
MOA: Activates type-2 chloride channels (ClC-2) in the apical membrane of intestinal epithelial cells.
→ Increases chloride-rich fluid secretion into the intestinal lumen
→ Enhances intestinal motility
→ Helps soften stool and promotes spontaneous bowel movements
Indication:
* Chronic idiopathic constipation (CIC)
* IBS with constipation (IBS-C) in women
* Opioid-induced constipation (OIC)

Question 3

Drug: tegaserod (Zelnorm)

Answer 3

Class: Serotonin 5-HT₄ receptor agonist
MOA: Stimulates 5-HT₄ receptors in the GI tract.
→ Enhances release of neurotransmitters like acetylcholine
→ Increases peristalsis and promotes intestinal secretion
→ Accelerates GI transit
Indication:
* IBS with constipation (IBS-C) in women under 65 (with low cardiovascular risk)

Question 4

Drug: Pancrelipase (Creon, Zenpep, Pancreaze)

Answer 4

Class: Pancreatic enzyme replacement
MOA: Replaces deficient digestive enzymes (lipase, amylase, protease).
Note: Derived from pork pancreas; used in cystic fibrosis and pancreatitis.