Which drug is a dopamine-1 receptor agonist used in hypertensive emergencies to maintain renal perfusion by dilating renal arterioles?

• A. Nifedipine
• B. Epinephrine
• C. Labetalol
• D. Fenoldopam

Answer: (D)

In a hypertensive emergency where maintaining renal perfusion is essential, you want a drug that lowers blood pressure while specifically increasing blood flow to the kidneys. Fenoldopam fits this by acting as a selective dopamine-1 receptor agonist, which dilates renal arterioles. This dilation raises renal perfusion and promotes natriuresis and diuresis, all while reducing systemic vascular resistance. It’s given by IV infusion with a rapid onset and short duration, allowing tight control of BP without compromising kidney blood flow.

Other options don’t provide this targeted renal vasodilation. Nifedipine lowers BP through systemic arterial dilation but doesn’t selectively enhance renal perfusion. Epinephrine can raise BP and often increases renal vascular resistance at typical therapeutic doses, not preserving renal flow. Labetalol lowers BP via alpha and beta blockade without renal-specific vasodilation. Fenoldopam is the agent that uniquely preserves renal perfusion while lowering BP in this context.