A 56-year-old man presents to the emergency department with severe chest pain and diaphoresis. He reports taking sildenafil 6 hours ago for erectile dysfunction. His blood pressure is 150/90 mmHg. Sublingual nitroglycerin should be withheld because of which concern?

• A Risk of precipitating coronary vasospasm
• B Increased risk of ventricular arrhythmia
• C Reduced antianginal efficacy of nitroglycerin
• D Profound hypotension due to additive guanylate cyclase activation ✓

Explanation

Sildenafil inhibits phosphodiesterase type 5, slowing cGMP breakdown in vascular smooth muscle. Nitrates increase cGMP production through guanylate cyclase, so combining them causes catastrophic vasodilation and refractory hypotension. Nitrates are contraindicated within 24 hours of sildenafil (48 hours for tadalafil). The correct approach is alternative analgesia and antianginals such as morphine and beta blockade while awaiting the washout period.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.