Erectile dysfunction: The Daily PANCE Blueprint

The answer is B. Severe hypotension risk.

Phosphodiesterase-5 (PDE-5) inhibitors, like sildenafil, and nitrates, like nitroglycerin, are both potent vasodilators that work through the nitric oxide/cyclic GMP pathway.

• Nitrates increase the production of cGMP.
• PDE-5 inhibitors prevent the breakdown of cGMP. When used together, their effects are synergistic, leading to a dramatic increase in cGMP, which can cause sudden, profound, and potentially life-threatening hypotension. This is an absolute contraindication and a critical patient safety issue.

Incorrect Answer Explanations:

• Increased risk of MI: While severe hypotension can lead to decreased coronary perfusion and potentially trigger an MI in a susceptible patient, the primary pharmacodynamic interaction and direct contraindication is the risk of severe hypotension itself.
• High risk of priapism: Priapism is a known potential side effect of sildenafil alone but is not the reason for the specific contraindication with nitrates.
• Causes acute renal failure: This combination does not have a direct nephrotoxic effect that leads to acute renal failure.
• Inactivates nitroglycerin: This is incorrect; sildenafil significantly potentiates the vasodilatory effect of nitroglycerin rather than inactivating it.