Which is a contraindication to nitroglycerin administration?

Which is a contraindication to nitroglycerin administration?

• A. The patient has used sildenafil within the last 24 hours
• B. Systolic blood pressure is 150/90 mmHg
• C. There is a history of aspirin allergy
• D. The patient has taken a diuretic today

Answer: (A)

The main concept is that combining nitroglycerin with certain medications that also cause vasodilation can lead to a dangerous drop in blood pressure. Nitroglycerin works by releasing nitric oxide, which increases cGMP and causes veins to dilate, lowering the heart’s workload. Sildenafil, a phosphodiesterase-5 inhibitor, also increases cGMP by preventing its breakdown. When both are used together, their effects on vascular tone compound, risking life-threatening hypotension. That’s why sildenafil within the last 24 hours is a contraindication to nitroglycerin administration. The remaining scenarios do not pose the same risk: a systolic BP of 150 mmHg/90 mmHg isn’t an absolute barrier to nitro as long as BP remains adequate; an aspirin allergy doesn’t affect nitroglycerin use; and taking a diuretic today doesn’t contraindicate nitroglycerin either.

The main concept is that combining nitroglycerin with certain medications that also cause vasodilation can lead to a dangerous drop in blood pressure. Nitroglycerin works by releasing nitric oxide, which increases cGMP and causes veins to dilate, lowering the heart’s workload. Sildenafil, a phosphodiesterase-5 inhibitor, also increases cGMP by preventing its breakdown. When both are used together, their effects on vascular tone compound, risking life-threatening hypotension.

That’s why sildenafil within the last 24 hours is a contraindication to nitroglycerin administration. The remaining scenarios do not pose the same risk: a systolic BP of 150 mmHg/90 mmHg isn’t an absolute barrier to nitro as long as BP remains adequate; an aspirin allergy doesn’t affect nitroglycerin use; and taking a diuretic today doesn’t contraindicate nitroglycerin either.