A 58-year-old man started on enalapril three weeks ago now complains of continuous clear watery rhinorrhoea and nasal blockage. There is no sneezing, itching, or eye symptoms, and skin prick tests are negative. Which property of the offending drug explains his symptoms?

• A Anticholinergic drying of nasal secretions with reflex hypersecretion
• B Direct alpha-adrenergic blockade producing mucosal vasodilation
• C Increased bradykinin levels causing nasal vascular permeability ✓
• D Histamine release from mast cell degranulation

Explanation

ACE inhibitors prevent degradation of bradykinin, and raised bradykinin increases nasal vascular permeability and glandular secretion, producing congestive and hypersecretory rhinitis without the sneezing and itch that mark allergic disease. This is a recognised form of drug-induced rhinitis and resolves on stopping the drug. Mast cell degranulation with histamine release would produce the sneezing, pruritus, and positive allergy testing that this patient lacks.

Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.