Know the Ins and Outs of Selecting IV Antihypertensives

You'll get questions about selecting an IV antihypertensive.

First, confirm the indication. Often an IV med isn't needed at all...such as for asymptomatic hypertension or "PRN" use.

But guide options for hypertensive emergency...very high BP with end organ damage, such as acute kidney injury or ischemic stroke.

Think of labetalol or nicardipine as your workhorses. Either starts lowering BP in about 5 to 10 min and can be used for most indications.

Generally go with labetalol IV bolus doses for modest BP lowering...in the range of 30 mmHg or less.

Start with 5 to 20 mg and double every 10 minutes up to 80 mg/dose if needed. "Labetalol failure" is often due to underdosing.

Consider IV labetalol 300 mg/day the usual max. This is based on how it was studied...not a hard-and-fast rule. But it's a good threshold to re-examine adding or switching meds.

If you want to slowly load labetalol, consider using an infusion for a few hours...then switch to scheduled dosing.

But don't jump to prolonged infusions of labetalol...it lasts 6 hours or more and accumulation can lead to refractory hypotension.

For more aggressive BP lowering with a continuous infusion, use nicardipine as your go-to.

Decrease the rate once BP hits target. "Overshooting" is common with nicardipine...since its duration is 30 minutes or more.

For example, include orders to reduce the nicardipine rate to 5 mg/hr once the goal is reached...and adjust every 5 to 15 min as needed.

Expect to hear clevidipine touted as a "better nicardipine."

Clevidipine wears off faster...about 10 min after stopping. And max doses require less volume... 42 mL/hr for clevidipine compared to up to 150 mL/hr for nicardipine.

But clarify that BP lowering seems similar. And max doses cost about $1,500/day for clevidipine versus $370 for nicardipine.

Avoid hydralazine. It can cause erratic BP lowering...is hard to titrate...and has a duration of up to 12 hours.

See our chart, Drug Options for Hypertensive Emergency, to review other IV agents that may be used first-line...such as esmolol for aortic dissection or nitroglycerin in acute coronary syndrome.

Key References

  • Eur Heart J Cardiovasc Pharmacother 2019;5(1):37-46
  • Hypertension 2018;71(6):1269-1324
  • Curr Hypertens Rep 2018;20(7):56
Hospital Pharmacist's Letter. July 2021, No. 370719



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