A 48-year-old man presents with severely elevated blood pressure and renal impairment. Which medication is contraindicated in his treatment?

In cases of severely elevated blood pressure combined with renal impairment, the use of nitroprusside is contraindicated due to the potential side effects associated with its metabolism. Nitroprusside is a potent vasodilator that can cause rapid reductions in blood pressure, but its breakdown leads to cyanide production, especially when used in high doses or over prolonged periods. In patients with renal impairment, the ability to clear cyanide is compromised, increasing the risk of cyanide toxicity.

The other medications listed, such as esmolol, labetalol, and nicardipine, are safer alternatives in managing hypertensive emergencies, especially in the presence of renal issues. Esmolol is a short-acting beta-blocker effective for controlling blood pressure without causing significant renal complications. Labetalol combines alpha and beta blockade, providing a balanced approach to reducing blood pressure. Nicardipine, a calcium channel blocker, can effectively lower blood pressure while being safer in patients with renal impairment as it does not produce toxic metabolites that can accumulate.