GI GI Pharmacology and Medications 2 — Questions and Answers
Question 1: Which medication is used to treat hepatic encephalopathy by reducing gut bacteria that produce ammonia, without being significantly absorbed systemically?
- Neomycin
- Rifaximin (Correct answer)
- Metronidazole
- Vancomycin
Correct answer: Rifaximin
Rifaximin is a minimally absorbed antibiotic that reduces ammonia-producing gut bacteria and is preferred for preventing recurrent hepatic encephalopathy.
Question 2: Cholestyramine is a bile acid sequestrant used to treat which type of diarrhea?
- Osmotic diarrhea from lactose intolerance
- Secretory diarrhea from VIPoma
- Bile acid malabsorption diarrhea (Correct answer)
- Infectious diarrhea from C. difficile
Correct answer: Bile acid malabsorption diarrhea
Cholestyramine binds bile acids in the colon, preventing them from stimulating fluid secretion, and is effective for bile acid malabsorption (e.g., post-ileal resection).
Question 3: Which drug class is used as first-line prophylaxis for spontaneous bacterial peritonitis (SBP) recurrence in cirrhotic patients with ascites?
- Antifungals
- Fluoroquinolone antibiotics (e.g., norfloxacin) or trimethoprim-sulfamethoxazole (Correct answer)
- Aminoglycosides
- Macrolide antibiotics
Correct answer: Fluoroquinolone antibiotics (e.g., norfloxacin) or trimethoprim-sulfamethoxazole
Long-term norfloxacin or trimethoprim-sulfamethoxazole is used for secondary SBP prophylaxis in cirrhotic patients after a prior episode.
Question 4: Lubiprostone and linaclotide are used to treat constipation-predominant IBS (IBS-C); what is their shared mechanism?
- Inhibit colonic motility
- Stimulate intestinal chloride secretion, increasing luminal fluid (Correct answer)
- Block opioid receptors in the gut
- Inhibit bile acid reabsorption
Correct answer: Stimulate intestinal chloride secretion, increasing luminal fluid
Both lubiprostone (ClC-2 activator) and linaclotide (GC-C agonist) increase intestinal chloride and fluid secretion, softening stool and accelerating transit.
Question 5: Alosetron is a 5-HT3 antagonist approved for IBS with diarrhea (IBS-D) in women; which serious adverse effect restricts its use?
- Severe hepatotoxicity
- Ischemic colitis and severe constipation (Correct answer)
- QT prolongation and arrhythmias
- Agranulocytosis
Correct answer: Ischemic colitis and severe constipation
Alosetron carries a black box warning for ischemic colitis and severe constipation, restricting it to women with severe IBS-D who fail other therapies.
Question 6: Terlipressin is used in hepatorenal syndrome and variceal bleeding; what is its mechanism of action?
- Blocks aldosterone receptors in the kidney
- Vasoconstrictor that reduces splanchnic blood flow via V1 vasopressin receptors (Correct answer)
- Stimulates hepatic albumin synthesis
- Blocks beta-1 adrenergic receptors in the heart
Correct answer: Vasoconstrictor that reduces splanchnic blood flow via V1 vasopressin receptors
Terlipressin is a vasopressin analogue that constricts splanchnic vasculature, reducing portal pressure and increasing renal perfusion in hepatorenal syndrome.
GI GI Pharmacology and Medications 2
Which medication is used to treat hepatic encephalopathy by reducing gut bacteria that produce ammonia, without being significantly absorbed systemically?