Drugs for Inflammatory Bowel Disease (IBD) – Notes

1) Definition and Types of IBD

• IBD is a chronic inflammatory disease of the intestine.
• Two main types:
  • Ulcerative colitis (UC)
  • Crohn’s disease (CD)

2) Ulcerative Colitis (UC): Key Features

• Involves colon only.
• Disease starts from rectum and extends upward in a continuous pattern.
• Lesions are mainly in mucosa and submucosa.

3) Crohn’s Disease (CD): Key Features

• Lesions are patchy (skip lesions) and transmural.
• Can affect any part of GI tract (often terminal ileum/colon).
• May lead to complications:
  • Strictures
  • Fissures
  • Perforation
  • Fistula

4) Shared/Overlapping Features of UC and CD

• Few patients show mixed features (sometimes called indeterminate colitis).
• Extraintestinal manifestations may occur in both:
  • Fever
  • Oral ulceration
  • Arthritis
  • Dermatitis
  • Hepatitis
  • Uveitis

5) Drug Groups Used in IBD

• 5‑Aminosalicylic acid (5‑ASA) compounds
• Corticosteroids
• TNF‑α inhibitors

6) Sulfasalazine (Salicylazosulfapyridine)

• Compound of 5‑ASA + sulfapyridine linked by azo bond.
• In colon, bacterial enzymes split it and release active 5‑ASA.
• Sulfapyridine mainly acts as carrier and contributes to adverse effects.

7) Mechanism of 5‑ASA/Sulfasalazine

• Inhibits COX and LOX pathways → ↓ prostaglandins and leukotrienes.
• Modulates inflammatory mediators:
  • Cytokines
  • PAF
  • TNF‑α
  • NF‑κB activity
• Overall effect: reduced mucosal inflammation and secretion, symptomatic relief.

8) Clinical Use

• Useful in mild to moderate active UC.
• Also used for maintenance of remission in UC.
• Effect in Crohn’s disease is limited.
• 5‑ASA preparations may be used especially in colonic disease.

9) Dosing Pattern (as shown)

• Active mild–moderate UC: around 3–4 g/day.
• Maintenance after remission: about 1.5–2 g/day.

10) Additional Points

• Corticosteroids are mainly for acute exacerbations.
• 5‑ASA drugs are often preferred for long-term control in suitable UC patients.

1. Exam-style short notes (5 marks)
2. Flowchart/mind map format
3. One-page revision sheet with mnemonics