What is the starting dose of hydralazine (antihypertensive medication)?

From the Guidelines

The starting dose of hydralazine for hypertension is typically 10 mg via slow IV infusion, with a maximum initial dose of 20 mg, and can be repeated every 4–6 h as needed. This recommendation is based on the most recent and highest quality study available, which is the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1.

Key Considerations

• The dose of hydralazine can be adjusted based on blood pressure response, with the goal of achieving optimal blood pressure control while minimizing potential side effects.
• Hydralazine works as a direct vasodilator, relaxing vascular smooth muscle primarily in arterioles, which reduces peripheral resistance and lowers blood pressure.
• When starting hydralazine, it's essential to monitor for potential side effects, including headache, tachycardia, and fluid retention.
• Due to these effects, hydralazine is often prescribed alongside a beta-blocker to prevent reflex tachycardia and a diuretic to manage fluid retention.

Important Details

• The study by 1 provides the most up-to-date and reliable information on the starting dose of hydralazine for hypertension.
• The initial dose of 10 mg via slow IV infusion is recommended, with a maximum initial dose of 20 mg, and can be repeated every 4–6 h as needed.
• It's crucial to note that the full therapeutic effect of hydralazine may take several days to develop, and patients should be advised accordingly.
• The 2013 ACCF/AHA guideline for the management of heart failure 1 provides additional information on the use of hydralazine in combination with isosorbide dinitrate, but it is not directly relevant to the starting dose of hydralazine for hypertension.

From the FDA Drug Label

When there is urgent need, therapy in the hospitalized patient may be initiated intramuscularly or as a rapid intravenous bolus injection directly into the vein. The usual dose is 20 to 40 mg, repeated as necessary Certain patients (especially those with marked renal damage) may require a lower dose.

The starting dose of hydralazine is 20 to 40 mg. This dose may be adjusted based on the patient's response, and certain patients, such as those with marked renal damage, may require a lower dose 2.

From the Research

Starting Dose of Hydralazine

The starting dose of hydralazine, an antihypertensive medication, can vary based on several factors including the patient's condition, renal function, and acetylator status.

• The dose of hydralazine needed to induce hemodynamic improvement in patients with severe heart failure is variable and requires individualization 3.
• In patients with hypertension, hydralazine can be started at a dose of 75 mg, with titration to higher doses such as 150 or 300 mg daily, based on the patient's response 4.
• A study comparing the efficacy and tolerability of conventional and slow-release hydralazine preparations found that blood pressure control achieved with multiple doses of conventional hydralazine was maintained with slow-release hydralazine, with no discrepancy between once- and twice-daily administration, when the same daily dose of hydralazine was given 5.
• The maximum antihypertensive response (Emax) to hydralazine was found to be 9.4 mm Hg, with the daily dose that elicited 50% of the maximum response (D50) being 0.87 mg/kg for slow acetylators and 1.68 mg/kg for fast acetylators 4.
• It is essential to note that hydralazine should be used with caution, especially in hospitalized patients, as its use is often unjustified and may cause harm if used inappropriately 6.
• The starting dose and dosing interval of hydralazine may need to be adjusted based on the patient's renal function, as the duration of action of hydralazine is longer in patients with impaired renal function 3.