Angioedema

Angioedema

Definition

Angioedema is a localized, transient swelling of the deeper layers of the skin or mucous membranes, typically involving the subcutaneous tissue, submucosa, or mucosa of the gastrointestinal or respiratory tract.

  • It is similar to urticaria but occurs deeper and may not be associated with itching.
  • Swelling often affects lips, tongue, face, extremities, genitalia, and sometimes the airway.

Pathophysiology

Angioedema can be classified by mediator type:

  1. Histamine-mediated (allergic)
    • Triggered by IgE-mediated hypersensitivity.
    • Rapid onset (minutes to hours).
    • Often associated with urticaria and pruritus.
    • Mediated by mast cell and basophil degranulation → histamine release.
  2. Bradykinin-mediated
    • Caused by excess bradykinin, leading to increased vascular permeability.
    • No urticaria or pruritus typically.
    • Examples:
      • ACE inhibitor-induced angioedema
        • Usually involves lips, tongue, or face.
        • Can occur anytime during therapy (even years after starting ACE inhibitors).
      • Hereditary angioedema (HAE)
        • C1 esterase inhibitor deficiency or dysfunction (types I and II).
      • Acquired angioedema
        • Often associated with lymphoproliferative disorders.

Common Causes

Type Examples
Drug-induced ACE inhibitors, ARBs (rare), NSAIDs, radiocontrast agents
Allergic / IgE-mediated Foods, insect stings, drugs (penicillin, sulfonamides)
Hereditary C1-INH deficiency or dysfunction
Acquired Autoimmune or lymphoproliferative disorders
Idiopathic Unknown cause; can be recurrent

Clinical Presentation

  • Swelling: sudden onset, soft, non-pitting, may be painful or burning.
  • Location: face, lips, tongue, extremities, gastrointestinal tract (causing abdominal pain), upper airway (can be life-threatening).
  • Airway involvement: hoarseness, dysphagia, stridor, dyspnea.
  • Histamine-mediated: often with urticaria, pruritus, flushing.
  • Bradykinin-mediated: no urticaria, slower onset (hours), recurrent episodes, sometimes abdominal pain.

Key Laboratory / Diagnostic Clues

  • C4 and C1-INH levels → low in hereditary or acquired bradykinin-mediated angioedema.
  • IgE testing for allergic triggers.
  • Clinical history: ACE inhibitor use, family history, recurrent episodes.

Management Considerations (Pharmacist Perspective)

Immediate / Emergency Care

  • Airway management is top priority for laryngeal edema.
  • Epinephrine, corticosteroids, antihistamines are effective in histamine-mediated angioedema.
  • Bradykinin-mediated angioedema (ACE inhibitor, HAE):
    • Not responsive to epinephrine, corticosteroids, or antihistamines.
    • Specific therapies:
      • C1-INH concentrate (for HAE)
      • Icatibant (bradykinin B2 receptor antagonist)
      • Fresh frozen plasma (in emergencies if specific agents unavailable)
    • ACE inhibitor-induced: discontinue ACE inhibitor permanently; ARBs may sometimes be used cautiously.

Chronic / Prophylaxis

  • HAE prophylaxis: C1-INH replacement, lanadelumab (monoclonal antibody), attenuated androgens (danazol, less commonly used now).
  • Avoid known triggers (drugs, foods, trauma).
  • ACE inhibitors: educate patients about risk, especially anytime during therapy.
  • ARB cross-reactivity: generally low but monitor carefully in ACE inhibitor-induced cases.
  • NSAIDs / COX-1 inhibitors: may trigger histamine-mediated angioedema, especially in patients with chronic urticaria.
  • Drug interactions: e.g., concurrent use of neprilysin inhibitors with ACE inhibitors increases risk of angioedema.

Pharmacist Role

  1. Medication review
    • Identify high-risk drugs (ACE inhibitors, ARBs, NSAIDs).
  2. Patient counseling
    • Recognize early signs: lip/tongue swelling, throat tightness.
    • Educate to seek urgent care for airway involvement.
  3. Monitoring
    • For recurrent angioedema: track episodes, triggers, and response to therapy.
  4. Coordination
    • Communicate with prescribers regarding drug discontinuation or substitution.
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