352 Irritable Bowel Syndrome

Question 1

It is a functional bowel disorder charac- terized by abdominal pain or discomfort and altered bowel habits in the absence of detectable structural abnormalities.

Answer 1

Irritable Bowel Syndrome

Question 2

Diagnostic Criteria for IBS

Answer 2

Recurrent abdominal pain or discomfort at least 3 days per month in the last
3 months associated with two or more of the following:
1. Improvement with defecation
2. Onset associated with a change in frequency of stool
3. Onset associated with a change in form (appearance) of stool

Question 3

It is the most consistent clinical feature in IBS.

Answer 3

Alteration in bowel habits

Question 4

True or False

Bleeding is not a feature of IBS unless hemorrhoids are present, and malabsorption or weight loss does not occur.

Answer 4

True

Question 5

Pathogenesis of IBS

Answer 5

• poorly understood
• abnormal gut motor and sensory activity, central neural dysfunction, psychological disturbances, mucosal inflammation, stress, and luminal factors

Question 6

This can lead to increased expression of TRPV1 in the enteric nervous system –> correlate with visceral hypersensitivity and abdominal pain.

Answer 6

Mucosal inflammation

Question 7

Microbes involved in Postinfectious IBS

Answer 7

Campylobacter, Salmonella, and Shigella

Question 8

Features that argue against IBS

Answer 8

anemia, elevated sedimentation rate, presence of leukocytes or blood in stool, and stool volume >200–300 mL/d.

Question 9

Treatment of IBS

Answer 9

Stool-Bulking Agents: Fiber

Antispasmodics: anticholinergic (dicyclomine)

Antidiarrheal Agents: loperamide

Antidepressant drugs: imipramine- motor inhibitory effect in IBS-D

Anti-flatulence therapy

Modulation of gut flora: neomycin dosed at 500 mg twice daily for 10 days

Serotonin Receptor Agonist and Antagonists

Chloride Channel Activators

Guanylate Cyclase-C Agonist

Question 10

It is the only antibiotic with demonstrated sustained benefit beyond ther- apy cessation in IBS patients.

Answer 10

Rifaximin

Question 11

It is a bicyclic fatty acid that stimulates chloride channels in the apical membrane of intestinal epithelial cells. Chloride secretion induces passive movement of sodium and water into the bowel lumen and improves bowel function.

Answer 11

Lubiprostone

Question 12

Drugs for diarrhea in IBS

Answer 12

Loperamide
Cholestyramine resin
Alosetron

Question 13

Drugs for constipation in IBS

Answer 13

Psyllium husk
Methylcellulose
Calcium polycarbophil
Lactulose syrup
70% sorbitol
Polyethylene glycol 3350
Lubiprostone
Magnesium hydroxide
Linaclotide

Question 14

Drugs for abdominal pain in IBS

Answer 14

Smooth-muscle relaxant
Tricyclic antidepressants
SSRI

Question 15

Drugs for gas and bloating in IBS

Answer 15

Low FODMAP diet
Probiotics
Rifaximin