Core67: Drug-induced adverse reaction: mucosal damage

🩹 High-yield / 要点：Drug-induced mucosal damage can affect the stomach, intestine, mouth, esophagus, or nasal mucosa. The mechanisms differ by site and drug.

General concept / 基本概念

• Certain medicines damage mucosa either:
  • At the site of introduction, or
  • At distant mucosal surfaces.
• Important compartments:
  • Gastric mucosa.
  • Intestinal epithelium.
  • Oral/esophageal mucosa.
  • Nasal epithelium.

Gastric mucosal damage / 胃粘膜障害

NSAIDs

• Cause gastric mucosal injury by two mechanisms:
  • Direct toxicity:
    • Acidic NSAIDs become concentrated in mucosal cells at neutral pH.
  • Indirect effect:
    • Inhibition of prostaglandin synthesis.
• Examples:
  • Ibuprofen (least toxic among listed NSAIDs)
  • Aspirin
  • Naproxen
  • Diclofenac

COX-2 selective inhibitors

• Cause less gastric mucosal damage than nonselective NSAIDs.
• Reason:
  • They inhibit COX-2.
  • Constitutive COX-1 can still synthesize protective gastric PGE2.

Other drugs associated with gastric mucosal damage

• Glucocorticoids
• Clopidogrel
• Tricyclic antidepressants
• Chemotherapeutic agents

Intestinal epithelial damage / 腸上皮障害

• Common with chemotherapeutics and antitumor drugs because they inhibit cell division.
• Examples:
  • 5-FU
  • Capecitabine
  • Anthracyclines
  • Irinotecan
  • Taxanes
  • NSAIDs

Other mucosal damage / その他の粘膜障害

Site	Drugs	Manifestation
Nasal epithelium	α-agonists (oxymetazoline, xylometazoline), cocaine	Nasal mucosal injury
Esophagus	Tetracyclines, clindamycin, metronidazole, bisphosphonates	Drug-induced esophagitis
Oral cavity	β-blockers, NSAIDs, chemotherapeutic drugs	Oral mucositis

Remember / 覚え方

• NSAIDs = classic gastric mucosal damage
• Chemo = intestinal epithelial injury
• Tetracyclines/bisphosphonates = esophagitis
• β-blockers/NSAIDs/chemo can cause oral mucositis