A patient started on ramipril develops recurrent episodes of non-pruritic swelling of the lips and face without urticaria. The accumulation of which mediator explains this presentation?

• A Histamine
• B Substance P
• C Leukotriene C4
• D Bradykinin ✓

Explanation

Angiotensin-converting enzyme degrades bradykinin. ACE inhibitors therefore raise bradykinin levels, and excess bradykinin increases vascular permeability, producing hereditary-type angioedema characterized by non-pruritic swelling without wheals. Histamine-mediated allergic angioedema is pruritic and accompanied by urticaria, which distinguishes it clinically. Leukotriene C4 drives bronchospasm, and substance P mediates neurogenic pain and vasodilation rather than isolated angioedema.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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