During a hypertensive crisis in pheochromocytoma, which medication is commonly used to acutely lower blood pressure?

• A. Phentolamine
• B. Lisinopril
• C. Furosemide
• D. Nitroglycerin

Answer: (A)

During a hypertensive crisis from pheochromocytoma, a surge of catecholamines causes strong alpha-adrenergic–mediated vasoconstriction. The quickest and most reliable way to lower blood pressure acutely is to block those alpha receptors. Phentolamine is a reversible, nonselective alpha-adrenergic blocker given intravenously, so it rapidly relaxes the blood vessels and reduces blood pressure. This approach directly counters the mechanism driving the crisis and allows controlled reduction of BP while monitoring the patient. It also avoids the problem of unopposed alpha activity that can occur if beta-blockers are given first. After stabilization, longer-acting alpha blockade can be used preoperatively. Other options don’t address the catecholamine-driven vasoconstriction as effectively in this emergency context: lisinopril targets the renin-angiotensin system, not the acute alpha-mediated vasoconstriction; furosemide reduces volume but not the underlying cause; nitroglycerin can lower BP but doesn’t block alpha receptors and may cause reflex tachycardia. Thus phentolamine is the best choice.