What class of medication is hydralazine?

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Last updated: July 2, 2025View editorial policy

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From the Guidelines

Hydralazine is a direct-acting vasodilator medication that belongs to the class of antihypertensive drugs known as arterial vasodilators. According to the most recent and highest quality study, 1, hydralazine works by directly relaxing the smooth muscle in arterial vessel walls, which causes blood vessels to dilate, reducing peripheral resistance and lowering blood pressure. This medication is often used in combination with other antihypertensive drugs, particularly beta-blockers and diuretics, as it can cause reflex tachycardia when used alone.

Some key points to consider when using hydralazine include:

  • Common dosing ranges from 10-75 mg four times daily for hypertension, with treatment typically starting at lower doses and gradually increasing as needed.
  • Patients should be aware that hydralazine may cause side effects including headache, dizziness, flushing, and palpitations due to its vasodilatory effects.
  • Long-term use requires monitoring for potential development of drug-induced lupus-like syndrome, particularly in slow acetylators.
  • Hydralazine is also used in the management of heart failure and hypertensive emergencies, particularly in pregnancy-related hypertension (preeclampsia).

It's worth noting that while other studies, such as 1, 1, 1, 1, 1, 1, 1, and 1, provide additional information on the use of hydralazine, the most recent and highest quality study, 1, provides the most relevant and up-to-date information on the class of medication that hydralazine belongs to.

From the FDA Drug Label

HydrALAZINE hydrochloride, USP, is an antihypertensive, for oral administration. The class of medication of hydralazine is antihypertensive 2.

  • It is used to lower blood pressure by exerting a peripheral vasodilating effect through a direct relaxation of vascular smooth muscle 2.
  • The main effect of hydralazine is on the cardiovascular system.

From the Research

Classification of Hydralazine

  • Hydralazine is classified as a direct-acting vasodilator 3, 4
  • It is an arterial dilator, which means it decreases afterload and improves cardiac output 3
  • Hydralazine is used to treat hypertension and heart failure, and is often used in combination with other medications such as isosorbide dinitrate 3, 5, 6

Mechanism of Action

  • Hydralazine works by relaxing the smooth muscle in blood vessels, causing them to dilate and reducing blood pressure 4
  • It also increases coronary blood flow and improves myocardial oxygen consumption 7
  • Hydralazine has been shown to reduce mortality and hospitalization for heart failure in certain patient populations 6

Clinical Uses

  • Hydralazine is used to treat essential hypertension 4
  • It is also used to treat heart failure, particularly in patients with nonischemic cardiomyopathy 3, 5, 6, 7
  • Hydralazine may be used in combination with other medications, such as isosorbide dinitrate, to provide balanced vasodilation and improve symptoms of heart failure 3, 5, 6

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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