A 55-year-old man started on enalapril two weeks ago presents with a dry persistent cough. Which mediator accumulating due to bradykinin degradation blockade is responsible?

• A Substance P alone
• B Bradykinin acting on B1 receptors in airway epithelium
• C Bradykinin together with prostaglandins generated via COX pathway ✓
• D Angiotensin II acting on AT1 receptors in the lung

Explanation

ACE is identical to kininase II, so inhibition raises bradykinin levels. Bradykinin stimulates sensory C fibers and promotes prostaglandin generation, producing the characteristic dry cough seen in up to 10 to 15 percent of patients, more common in East Asian populations. Angiotensin II falls rather than rises on ACE inhibitors, so option D is physiologically impossible. Substance P contributes but bradykinin with prostaglandins is the accepted combined answer in standard texts.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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