What are two common contraindications to nitroglycerin administration in the field?

• A. Hypertension and dehydration
• B. Asthma and COPD
• C. Hypotension and recent use of PDE-5 inhibitors
• D. High heart rate and hyperglycemia

Answer: (C)

Nitroglycerin works by dilating veins and, to a lesser extent, arteries, which lowers preload and systemic blood pressure. In the field, that means giving nitro when blood pressure is already low can tip the patient into dangerous hypotension and reduced coronary perfusion. Another major issue is the interaction with phosphodiesterase type-5 inhibitors (such as sildenafil, tadalafil, or vardenafil). These drugs also cause vasodilation, and when combined with nitroglycerin they can produce a severe drop in blood pressure due to excessive accumulation of cGMP. For these reasons, the two common contraindications are hypotension and recent use of PDE-5 inhibitors. Other options listed don’t reflect standard contraindications in the field; nitroglycerin isn’t inherently contraindicated by asthma/COPD or by tachycardia or hyperglycemia, though those conditions may require caution or assessment.