Which of the following is a contraindication to nitroglycerin due to potential dangerous interaction with erectile dysfunction medications?

• A. Use of erectile dysfunction medications within the last 24-48 hours
• B. Severe hypotension (SBP < 100)
• C. Extreme bradycardia (HR < 50)
• D. Tachycardia in the absence of heart failure (HR > 120)

Answer: (A)

The key concept is the dangerous interaction between nitroglycerin and erectile dysfunction medications. Nitrates raise nitric oxide levels and increase cGMP, leading to vasodilation and lower blood pressure. Erectile dysfunction drugs (PDE5 inhibitors) also enhance the same cGMP pathway by inhibiting its breakdown. When both are present, the combined effect can cause a rapid and significant drop in blood pressure, risking fainting, shock, or myocardial ischemia. Because PDE5 inhibitors remain active in the body for about 24 to 48 hours (depending on the specific drug), using nitroglycerin within that window is a true contraindication.

While severe hypotension is itself a reason not to give nitroglycerin, and extreme bradycardia or tachycardia without heart failure can complicate management, the special concern in this question is the interaction with erectile dysfunction medications. That interaction is what makes recent or current ED med use the correct contraindication.