Cardiovascular Drugs USMLE Step 1 Practice Question
A 58-year-old man with chronic stable angina presents with chest pain during exertion despite 2 weeks of continuous long-acting nitrate patch use. Vital signs: BP 142/88 mmHg, HR 92 bpm, RR 16, SpO2 98% on room air. Recent troponin and ECG are normal. He denies headache or dizziness. The patch no longer relieves his anginal symptoms. Which of the following best explains the loss of therapeutic efficacy of his nitrate therapy?
Answer choices
- AIncreased sympathetic nervous system activation
- BMalabsorption of nitrates through the transdermal route
- CDownregulation of guanylate cyclase enzyme expression
- DTolerance due to depletion of mitochondrial sulfhydryl donorsCorrect answer
- EDevelopment of antibodies against the nitrate compound
- FIncreased phosphodiesterase-5 activity leading to enhanced cGMP degradation
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