From the Guidelines
Hydralazine should be taken at a dose of 25 mg three times daily, as recommended by the American Heart Association for the management of resistant hypertension, and can be titrated upward to a maximum dose as needed. This means taking one 25 mg tablet approximately every 8 hours, typically with meals and at bedtime to maintain consistent blood pressure control throughout the day. The total daily dose can range from 75 mg to 200 mg, depending on the individual's response to the medication and their specific condition, such as congestive heart failure with reduced ejection fraction, in which case hydralazine should be administered on a background of isosorbide mononitrate 30 mg daily, as stated in the study by 1. Hydralazine works by directly relaxing the smooth muscles in your blood vessel walls, causing them to widen and reduce blood pressure. This medication may take several weeks to reach its full effect. Common side effects include headache, dizziness, fast heartbeat, and fluid retention, as noted in the guidelines by 1 and 1. It's essential to take hydralazine exactly as prescribed and not to stop suddenly without consulting your healthcare provider. Regular blood pressure monitoring is recommended while taking this medication. If you miss a dose, take it as soon as you remember, but if it's almost time for your next dose, skip the missed dose and continue with your regular schedule. Hydralazine is often prescribed alongside other blood pressure medications like beta-blockers or diuretics for more effective blood pressure control.
Some key points to consider when taking hydralazine include:
- The medication can cause sodium and water retention, and reflex tachycardia, so it's often used with a diuretic and beta blocker, as mentioned in the study by 1.
- Hydralazine is associated with drug-induced lupus-like syndrome at higher doses, as noted in the guidelines by 1 and 1.
- The medication should be used with caution in patients with certain medical conditions, such as heart failure or kidney disease, and under the guidance of a healthcare provider.
- Regular monitoring of blood pressure, kidney function, and other health parameters is crucial while taking hydralazine, as recommended by 1, 1, and 1.
From the FDA Drug Label
Although the precise mechanism of action of hydrALAZINE is not fully understood, the major effects are on the cardiovascular system. HydrALAZINE apparently lowers blood pressure by exerting a peripheral vasodilating effect through a direct relaxation of vascular smooth muscle HydrALAZINE is rapidly absorbed after oral administration, and peak plasma levels are reached at 1 to 2 hours. Plasma levels of apparent hydrALAZINE decline with a half-life of 3 to 7 hours.
The dosing of Hydralazine 25 four times daily is not directly addressed in the provided drug label.
- The label does mention that HydrALAZINE is subject to polymorphic acetylation and slow acetylators generally have higher plasma levels of hydrALAZINE and require lower doses to maintain control of blood pressure.
- However, without explicit dosing recommendations, no conclusion can be drawn about the appropriateness of this specific dosing regimen 2.
From the Research
Hydralazine Dosage
- The dosage of hydralazine 25 four times daily is not directly mentioned in the provided studies.
- However, a study from 1982 3 assessed the effects of hydralazine formulation and dose interval in 20 patients with hypertension, and found that once-daily treatment with conventional hydralazine was unsatisfactory due to its hypotensive effect waning at 24 hours.
- The study concluded that there is no need to administer hydralazine more than twice daily, but it did not specifically address the dosage of 25mg four times daily.
Hydralazine in Heart Failure Treatment
- A study from 2016 4 devised a mnemonic (BANDAID(2)) to summarize evidence-based treatments for systolic heart failure, which includes nitrate-hydralazine as a treatment option.
- Another study from 2007 5 found that the fixed-dose combination of isosorbide dinitrate/hydralazine reduced mortality and morbidity in African-American patients with heart failure.
- A study from 2005 6 suggested that the combination of isosorbide dinitrate and hydralazine may be an adjunctive treatment option for African Americans with New York Heart Association class III and IV heart failure, when added to standard medical therapy.
Beta-Blockers and Hydralazine
- A study from 2010 7 discussed the use of beta-blockers in the treatment of systolic heart failure, but did not specifically address the combination of beta-blockers and hydralazine.
- The study from 2007 5 found that beta-blockers provided additional significant benefit in African-Americans with heart failure treated with the fixed-dose combination of isosorbide dinitrate/hydralazine.