A patient with recurrent attacks of laryngeal and facial oedema, normal complement C4 during remission and no urticaria, is diagnosed with hereditary angioedema due to C1 esterase inhibitor deficiency. Which agent directly blocks the mediator responsible for the attacks?
- A Adrenaline, an alpha and beta adrenergic agonist
- B Icatibant, a bradykinin B2 receptor antagonist ✓
- C Hydroxyzine, an H1 antihistamine
- D Prednisolone, a glucocorticoid
Correct answer: B. Icatibant, a bradykinin B2 receptor antagonist
Explanation
Hereditary angioedema is mediated by bradykinin generated through factor XII and kallikrein activation when C1 esterase inhibitor is deficient. Icatibant is a selective bradykinin A2 receptor antagonist used for acute attacks. Antihistamines and steroids are mainstays of histamine-mediated allergic angioedema but have no role here, since there is no mast cell involvement, which is precisely why options C and D are wrong.
Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.
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