Hydralazine Administration Guidelines

Intravenous Administration for Hypertensive Emergencies

The American College of Cardiology recommends an initial dose of 10-20 mg as a slow IV bolus for hypertensive emergencies, repeated every 4-6 hours as needed 1
Blood pressure begins to decrease within 10-30 minutes after administration, with the hypotensive effect lasting 2-4 hours 1
The unpredictability of response and prolonged duration make hydralazine undesirable as a first-line agent for acute hypertension in most patients 1

The American Heart Association recommends starting with 25-50 mg orally three to four times daily, always combined with isosorbide dinitrate for mortality benefit in HFrEF 2
The fixed-dose combination starts at 37.5 mg hydralazine/20 mg isosorbide dinitrate three times daily, with a target dose of 75 mg hydralazine/40 mg isosorbide dinitrate three times daily 4, 2
The combination regimen provides a 43% relative risk reduction in mortality, with an NNT of 25 over 10 months, and an NNT of 7 for preventing all-cause mortality over 36 months 4, 2

Hydralazine must be combined with isosorbide dinitrate for mortality benefit in heart failure, with a maximum daily dose of 300 mg hydralazine in divided doses 2, 3
Three to four times daily dosing is standard for heart failure management, with twice-daily dosing adequate for blood pressure control when combined with beta-blockers and diuretics 4, 2