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Difficulty: EasyPharmacologic Interventions

A 58-year-old man presents to his primary care physician to discuss recent difficulties with erectile dysfunction. He reports an inability to maintain an erection sufficient for sexual intercourse over the past four months. His past medical history is significant for stable angina pectoris, hypertension, and hyperlipidemia. His daily medication regimen includes several drugs for his cardiovascular conditions. His blood pressure is 128/82 mmHg and heart rate is 72/min. Physical examination is unremarkable. The physician considers prescribing sildenafil. Concurrent use of which of the following medications is an absolute contraindication to initiating this therapy?

  1. A
    Aspirin
  2. B
    Atorvastatin
  3. C
    Diltiazem
  4. Isosorbide dinitrateAnswer
  5. E
    Metoprolol

Answer

Isosorbide dinitrate
Isosorbide dinitrate is a nitrate medication commonly used for the management of angina. Phosphodiesterase-5 (PDE-5) inhibitors, such as sildenafil, act by preventing the degradation of cyclic guanosine monophosphate (cGMP), which prolongs smooth muscle relaxation and vasodilation. Nitrates act by increasing cGMP production. When used together, these two medication classes cause a synergistic, profound, and potentially fatal drop in blood pressure. Therefore, concurrent use of any nitrate is an absolute contraindication to PDE-5 inhibitor therapy.

Step-by-Step Solution

1
Identify the proposed pharmacological intervention.
The physician is considering sildenafil, a phosphodiesterase-5 (PDE-5) inhibitor, for erectile dysfunction.
Establishing the drug class is the first step in identifying relevant safety profiles and contraindications.
2
Recall absolute contraindications for PDE-5 inhibitors.
Concurrent use of any form of nitrates is absolutely contraindicated due to the risk of profound hypotension.
Both drug classes increase intracellular cyclic guanosine monophosphate (cGMP), leading to severe synergistic vasodilation.
3
Evaluate the options to identify a nitrate medication.
Isosorbide dinitrate is a nitrate commonly used for stable angina.
Matching the general contraindication to the specific medication listed provides the correct answer.

Key Concept

Absolute contraindications to phosphodiesterase-5 (PDE-5) inhibitors.
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Topics

Pharmacologic Interventions

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