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?
- A)Increased sympathetic nervous system activation
- B)Malabsorption of nitrates through the transdermal route
- C)Downregulation of guanylate cyclase enzyme expression
- D)Tolerance due to depletion of mitochondrial sulfhydryl donorsGABARITO
- E)Development of antibodies against the nitrate compound
Explicação
Nitrate tolerance develops with continuous use due to depletion of mitochondrial sulfhydryl donors (particularly cysteine and glutathione), which are necessary cofactors for bioconversion of nitrates to nitric oxide. Without these donors, nitrates cannot be me... Ver explicação completa e trilha adaptativa →