What is hydralazine-oral, and how does it work (mechanism of action)?
Hydralazine (Apresoline) is an antihypertensive
medication used to treat high blood pressure. It is a peripheral arterial
vasodilator and causes relaxation of blood vessels which carry blood away from
the heart and towards the organs and tissues. The exact mechanism of how hydralazine causes arterial smooth muscle relaxation is not yet understood.
Hydrazine affects calcium movement within blood vessels. Calcium is required for
muscle contraction and therefore disturbances in calcium movement may cause
smooth muscle relaxation in the blood vessels. Hydralazine is selective for
arterioles (small arteries), and the overall effects of treatment include a
decrease in arterial blood pressure, and peripheral vascular resistance.
In addition to treating high blood pressure, hydralazine has shown to be
beneficial for the treatment of congestive heart failure (CHF). Although
inhibitors are preferred for the treatment of CHF, hydralazine in combination
(Isordil, Isordil Titradose, Dilatrate-SR) is an alternative for patients who cannot tolerate ACE
Hydralazine was approved by the US Food and Drug Administration (FDA) in 1952
as an antihypertensive agent. It is commonly used for the treatment of
hypertension in pregnancy. Parenteral or injectable hydralazine is used to treat
hypertensive emergencies (severally high blood pressure) during pregnancy.
What brand names are available for hydralazine-oral?
Is hydralazine-oral available as a generic drug?
GENERIC AVAILABLE: Yes
Do I need a prescription for hydralazine-oral?
What are the uses for hydralazine-oral?
Hydralazine is used for the treatment of essential
hypertension (high blood pressure), alone or in-combination with other
anti-hypertensive medications. It is also used for treating hypertensive crisis
and congestive heart failure.
What are the side effects of hydralazine-oral?
Common side effects of hydralazine are:
- tachycardia (rapid heartbeat), and
- angina pectoris (chest pain).
Other less commonly reported side effects include:
- paralytic ileus,
- low blood pressure,
- paradoxical pressor response,
- dyspnea (shortness of breath),
- peripheral neuritis,
- muscle cramps,
- psychotic reactions,
- difficulty urinating,
- blood disorders,
- hypersensitivity type reactions,
- nasal congestion,
- abnormal tear production (lacrimation) , and
Salt and sodium are the same.
What is the dosage for hydralazine-oral?
Hypertension in adult patients:
- Start treatment at a low dose and increase gradually based on individual
patient response. The usual recommended starting regimen is 10 mg orally four
times daily for the first 2 to 4 days, increase to 25 mg four times daily for
the remainder of the first week.
- For the second and subsequent weeks, increase dosage to 50 mg four times
daily (increase dose by 10-25 mg/dose gradually every 2-5 days).
- The maximum daily dose used in clinical studies is 300 mg.
Congestive heart failure:
- The initial dose for treating heart failure is 10 to 25 mg orally 3 to 4
- The usual dose is 225 to 300 mg daily in 3 to 4 divided doses.
For pediatric hypertensive emergencies, the dose is 0.5 mg/Kg IV every 4
Which drugs or supplements interact with hydralazine-oral?
Sympathomimetics such as:
- dobutamine (Dobutrex),
- dopamine (Intropin),
- norepinephrine (Levophed),
- epinephrine (Adrenalin),
- metaraminol (Aramine),
- ephedra (Ma Huang), and
- ephedrine may decrease the effectiveness of hydralazine.
Co-administration of these agents may block the anti-hypertensive benefits of
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Is hydralazine-oral safe to take if I’m pregnant or breastfeeding?
Hydralazine should be used in pregnancy only if the potential
benefit justifies the potential risk to the fetus. Hydralazine is classified as
FDA pregnancy risk category C (Animal reproduction studies have shown an adverse
effect on the fetus and there are no adequate and well-controlled studies in
humans, but potential benefits may warrant use of the drug in pregnant women
despite potential risks). It is used for treating high blood pressure during
What else should I know about hydralazine-oral?
What preparations of hydralazine-oral are available?
Tablets: 10, 25, 50, 100 mg; Solution for injection: 20 mg/ml
How should I keep hydralazine-oral stored?
Tablets and injection solution may be stored at room temperature
between 20 C to 25 C (68 F to 77 F).