From the Guidelines
Hydralazine is a vasodilator medication used to treat high blood pressure and heart failure, with a typical initial dose of 10 mg via slow IV infusion, which can be repeated every 4-6 hours as needed, as stated in 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 Points About Hydralazine
- It works by relaxing and dilating blood vessels, allowing blood to flow more easily and reducing blood pressure.
- Hydralazine is often prescribed when other blood pressure medications haven't been effective enough, particularly in cases of severe hypertension.
- It's also used to treat heart failure in combination with other medications, such as isosorbide dinitrate, with dosing information available in the 2021 update to the 2017 ACC expert consensus decision pathway for optimization of heart failure treatment 2.
- The medication should be taken consistently, even when feeling well, as hypertension is often symptomless but can lead to serious health problems if left untreated.
Administration and Dosage
- The typical starting dose is 10 mg via slow IV infusion, which can be repeated every 4-6 hours as needed, according to the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline 1.
- For oral administration, the starting dose is often 10-25 mg taken four times daily, which may be gradually increased to 50-100 mg per dose if needed.
Side Effects and Monitoring
- Side effects can include headache, rapid heartbeat, flushing, dizziness, and fluid retention.
- Long-term use requires monitoring as it can rarely cause a lupus-like syndrome.
- Blood pressure should be monitored after initiation and during titration of hydralazine and isosorbide dinitrate, as stated in the 2021 update to the 2017 ACC expert consensus decision pathway for optimization of heart failure treatment 2.
From the FDA Drug Label
Hydralazine hydrochloride injection, USP is an antihypertensive available in a 1 mL vial for intravenous and intramuscular administration. Hydralazine hydrochloride, USP is 1-hydrazinophthalazine monohydrochloride Hydralazine (Apresoline) is an antihypertensive medication, specifically a vasodilator. It is available for intravenous and intramuscular administration.
- The active ingredient is Hydralazine hydrochloride USP.
- The molecular formula is C8H8N4•HCl. 3
From the Research
Definition and Mechanism of Action
- Hydralazine, also known as Apresoline, is a direct-acting vasodilator that acts by dilating resistance arterioles, thus reducing peripheral resistance, with no dilating effect on the venous side of the circulation 4.
- It is used to treat hypertension, pre-eclampsia, and heart failure 5.
Therapeutic Uses
- Hydralazine is indicated in the long-term therapy of essential hypertension, in the short-term therapy of pregnancy-induced hypertension and eclampsia, and in the therapy of hypertensive crisis 4.
- It has been widely used in the treatment of hypertension in eclampsia and preeclampsia, and its safety has been demonstrated in these patients 6.
Adverse Effects
- Adverse effects of hydralazine include tachycardia, fluid retention, and headache, caused by the vasodilation, especially in the early days of therapy 4.
- There is a low risk of lupus-like syndrome with high doses and long-term use of hydralazine, as it is N-acetylated 4.
- Hydralazine can also cause severe acute kidney injury (AKI) resulting in chronic kidney disease (CKD) or death 7.
Administration and Combination Therapy
- Hydralazine therapy is usually combined with a sympathetic inhibitor to prevent expression of the reflex tachycardia, as well as with a diuretic agent to prevent sodium retention caused by reduction in renal perfusion pressure 4.
- It can be used in combination with other antihypertensive agents, such as beta-blockers, diuretics, and ACE inhibitors 8.