A 40-year-old nurse complains of gastrointestinal issues including nausea, abdominal pain, bloating, constipation, and left lower quadrant pain with bowel movements for the past 4 years. Examinations and tests were negative. Her symptoms are consistent with irritable bowel syndrome (IBS). IBS is diagnosed based on recurrent abdominal pain associated with changes in stool frequency or form. It can be caused by issues with intestinal motility, perception, or microbiota. Treatment focuses on controlling symptoms and may include diet, lifestyle changes, psychotherapy, and various drug therapies depending on the IBS subtype.

1. Pharmacological Management
of Irritable Bowel Disease
Dr. M. Ahsan (MBBS, MD)

2. Case 1:
A 40 year old nurse at a busy community complains of nausea, epigastric pain, post-
prandial fullness/bloating, constipation, and left lower quadrant pain with bowel
movements since the last 4 years. The symptoms started following an episode of severe
diarrhea after a family picnic.
She usually has to take sick-leave due to her symptoms.
Her bowel habits include 2-3 small hard stools per week, generally mid-day, and she feels is
never completely emptied.
Pain is improved when she has a bowel movement, but she often strains to have a bowel
movement. She often gets abdominal pain which is even worse when she forgets to take
her fiber and drink plenty of water.
She has tried a paleo diet but felt it only helped for a few months.
She has had a colonoscopy and a recent H.pylori breath test. Both were negative.

3. Learning Outcomes…
• Describe the clinical features of IBS
• Diagnose IBS
• Describe the mechanism of action, uses and adverse effects of
different drugs used in IBS
• Describe the management of different types of IBS

4. Irritable Bowel syndrome
• Irritable bowel syndrome (IBS) denotes a mixed group of abdominal
symptoms for which no organic cause can be found
IBS could be due to:
Disorders of intestinal motility
Enhanced visceral perception
Microbial dysbiosis
Prevalence = 10-20%
Age at onset = ≤ 40 years
M:F = 1:2

6. Irritable Bowel syndrome: Diagnosis
IBS should be diagnosed only if, recurrent abdominal pain is associated
with at least 2 of:
Relief by defecation
Altered stool form
Altered bowel frequency
• Other symptoms: urgency, incomplete evacuation, abdominal
bloating, mucus with stool, worsening of symptoms after food
 Symptoms are chronic (> 6 months)
 Often exacerbated by:
 Stress
 Menstruation
 Gastroenteritis
 Antibiotics

7. Types of IBS

8. Management of IBS
• Diet
• Psychosocial modifications
• Drug therapy
Treatment should focus on controlling symptoms:
Initially using lifestyle/dietary measures, then cognitive therapy or
pharmacotherapy if required

9. Drug therapy for IBS
• Linaclotide
• Lubiprostone
• Alosetron
• Eluxadoline
• Rifaximin
• Dicyclomine
• Hyoscyamine

10. Linaclotide
MOA:
• Increases intestinal fluid secretion via increased cGMP
Use: IBS-C
Adverse effects:
• Diarrhoea, abdominal pain, flatulence, abdominal distension
• Contraindication: children < 17 years of age

11. Lubiprostone
MOA:
• Chloride channel activator
Use: Women with IBS-C
Adverse effects:
• Diarrhoea, abdominal pain, dyspepsia, headache, dizziness, and
hypotension

12. Alosetron
MOA:
• 5-HT3 antagonist
Use: Women with severe IBS-D
Adverse effects:
• Constipation, nausea & vomiting

13. Eluxadoline
MOA:
• µ opioid receptor agonist
Use: IBS-D
Adverse effects:
• Constipation, abdominal pain, risk of dependence & overdose

14. Rifaximin
MOA:
• Structural analog of rifampin  decreases bacterial load
Use: Short term use in IBS-D
Adverse effects:
• Nausea, fatigue, headache, dizziness, risk of Clostridium difficile
infection

15. Dicyclomine
MOA:
• Anticholinergic drug (decreases GI spasms and motility)
Use: IBS-C and IBS-D
Adverse effects:
• Anticholinergic side effects such as drowsiness and dry mouth

16. Hyoscamine
MOA:
• Anticholinergic antispasmodic drug
Use: IBS-C and IBS-D
Adverse effects:
• Anticholinergic side effects; overdose may produce hallucinations

17. Management: Constipation
• Ensure adequate water and fibre intake
• Promote physical activity
• Simple laxatives (avoid lactulose: it ferments and can aggravate
bloating)
• If the above fail: try one of the following 
 Increased fibre intake can worsen
bloating
 Avoid insoluble fibre such as bran
 Oats are better
prucalopride
linaclotide
lubiprostone

18. Management: Diarrhoea
• Avoid sorbitol sweeteners, alcohol and caffeine
• Reduce dietary fibre content
• Avoid ‘trigger foods’
• Use a bulking agent + loperamide after each loose stool

19. Management Colic/Bloating
• Diets low in fermentable, poorly absorbed saccharides and alcohol
(low FODMAP diet) can help
• Oral antispasmodics
• Combination probiotics can help flatulence
 FODMAP: fermentable oligo-, di-, and
monosaccharides and polyols
 Low FODMAP diet excludes garlic, onions,
beans, fruits, wheat-containing products
and sweeteners

20. Management of psychological symptoms/
visceral hypersensitivity
• Patients should be treated sympathetically
• Cognitive behavioral therapy
• Low dose of tricyclic antidepressant: amitryptyline

21. Thank you

22. References
• Lippincott Illustrated Reviews: Pharmacology(6th ed.). Philadelphia,
PA: Wolters Kluwer.
• Clinical Medicine: A Textbook for Medical Students &amp; Kumar PJ
and Clark ML (9th ed.); Elsevier Saunders
• Oxford Handbook of Clinical Medicine, 10th edition