What is the typical oral dose of hydralazine (po) for hypertension?

From the Guidelines

The typical oral dose of hydralazine for hypertension is 100-200 mg, administered 2 or 3 times daily. This dosing regimen is based on the most recent and highest quality study available, which prioritizes the management of resistant hypertension 1. According to this study, hydralazine is a direct vasodilator that can be used to treat hypertension, particularly in cases where other treatments have failed.

Key Considerations

• Hydralazine is associated with sodium and water retention, as well as reflex tachycardia, and should therefore be used in conjunction with a diuretic and a beta-blocker 1.
• The maximum daily dose of hydralazine should not exceed 300 mg, and patients should be monitored for side effects such as headache, tachycardia, and fluid retention.
• Long-term use of hydralazine requires monitoring for potential development of drug-induced lupus-like syndrome, particularly at higher doses 1.

Clinical Context

In clinical practice, hydralazine may be particularly useful in patients with renal impairment or pregnancy-induced hypertension. However, its use should be carefully considered in the context of the patient's overall health status and medical history. As noted in the study by Carey et al., hydralazine can be an effective addition to a treatment regimen for resistant hypertension, but its use should be guided by careful assessment of the patient's individual needs and response to treatment 1.

Dosing and Administration

The dosing regimen for hydralazine should be individualized based on the patient's response to treatment and tolerance of side effects. Treatment usually begins with a lower dose, which can be gradually increased as needed to achieve optimal blood pressure control. Patients should be closely monitored for signs of adverse effects, and the dose should be adjusted accordingly.

From the FDA Drug Label

Initiate therapy in gradually increasing dosages; adjust according to individual response. Start with 10 mg four times daily for the first 2 to 4 days, increase to 25 mg four times daily for the balance of the first week. For the second and subsequent weeks, increase dosage to 50 mg four times daily. The incidence of toxic reactions, particularly the L. E. cell syndrome, is high in the group of patients receiving large doses of hydrALAZINE hydrochloride tablets. In a few resistant patients, up to 300 mg of hydrALAZINE hydrochloride tablets daily may be required for a significant antihypertensive effect.

The typical oral dose of hydralazine for hypertension is:

• Initial dose: 10 mg four times daily for the first 2 to 4 days
• First week: 25 mg four times daily
• Second and subsequent weeks: 50 mg four times daily
• Maximum dose: up to 300 mg daily in resistant patients 2

From the Research

Hydralazine Dosage for Hypertension

• The typical oral dose of hydralazine for hypertension is not explicitly stated in the provided studies, but the dosage regimens used in the studies can be referenced.
• In one study 3, patients were given conventional hydralazine 100 mg twice daily or 200 mg once daily.
• Another study 4 investigated the effect of giving hydralazine orally, 300 mg per day divided into 2,3, and 4 doses, in 4 hypertensive patients.
• A study from 2018 5 reported that oral hydralazine was the most common medication used for the treatment of acute hypertension in hospitalized medicine patients, with 521 doses administered, but the specific dosage is not mentioned.

Administration Frequency

• The study from 1982 3 concluded that there is no need to administer hydralazine more than twice daily, as once-daily treatment with conventional hydralazine was unsatisfactory due to its hypotensive effect waning at 24 hours.
• The 1975 study 4 found that a daily dose of 300 mg of hydralazine was as effective and free of side effects given in 2 as in 4 divided doses.

Clinical Considerations

• Hydralazine may reduce blood pressure when compared to placebo in patients with primary hypertension, but its effect on clinical outcomes remains uncertain 6.
• The use of as-needed hydralazine for the treatment of acute hypertension in hospitalized medicine patients is common, but administration thresholds are often less than what are used to define acute severe hypertension 5.