Practice Question
A 58-year-old man with stable angina takes isosorbide mononitrate daily and sublingual nitroglycerin as needed. He requests a prescription for sildenafil for erectile dysfunction. His blood pressure today is 128/76 mmHg and heart rate is 72 bpm. What is the most appropriate response by the nurse practitioner?
Answer Choices:
Correct Answer:
Do not prescribe any PDE-5 inhibitor while he is taking nitrates
Rationale:
🔹 Concurrent use of nitrates and PDE-5 inhibitors (e.g., sildenafil, tadalafil) is absolutely contraindicated due to the risk of profound, life-threatening hypotension.
🔹 Isosorbide mononitrate and nitroglycerin increase nitric oxide, leading to vasodilation, while PDE-5 inhibitors prevent cGMP breakdown, dramatically amplifying this effect.
🔹 Even in patients with normal blood pressure and stable angina, the combination can cause sudden severe hypotension, syncope, myocardial ischemia, or shock.
🔹 No safe timing interval exists that reliably eliminates this risk in patients on chronic nitrate therapy.
🔹 The safest and most appropriate response is to withhold all PDE-5 inhibitors and discuss alternative erectile dysfunction treatments that do not interact with nitrates.
❌ Why the other options are incorrect
❌ Prescribe tadalafil instead, as it is safer to use with nitrates
🔹 Tadalafil has a longer half-life (up to 36 hours) and is equally contraindicated with nitrates.
❌ Allow sildenafil use as long as he separates it from nitrate doses by at least 4 hours
🔹 Separation does not eliminate the interaction risk; dangerous hypotension can still occur.
❌ Advise patient to monitor blood pressure if taking both sildenafil and nitrate
🔹 Monitoring does not prevent sudden cardiovascular collapse and is unsafe clinical practice.
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This question is from ☑️ EXAM 3 2025 which contains 42 questions.
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Question Details
- Category: RN Nursing Exam(s)
- Subcategory: General Exams
- Domain: 🚑Pharmacology
- Answer Choices: 4