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Hydralazine (Apresoline)

Anesthesia Implications

Updated On: July 10, 2026

Classification:
hydrazinophthalazine, Antihypertensive, Vasodilator
Therapeutic Effects:
⬇BP ⬇SVR ⬆HR ⬆RAAS; Provides SUSTAINED decreases in BP
Time to Onset:

10 – 80 min (this burns a lot of people – you have to wait for the effects. Don’t redose too early!)

Duration:

up to 12 hrs

Primary Considerations:

Arteriolar dilator, which reduces blood pressure but increases heart rate. Used for moderate to Severe hypertension introp, HF with reduced ejection fraction, Hypertensive emergencies in pregnancy, postoperative hypertension. Can cause adverse effects: lupus-like syndrome (glomerulonephritis) esp. in patients with high doses; blood dyscrasias, hypotension, peripherial neuritis; MI/angina induced by tachycardia Should be avoided in patients with Lupus

Contraindications:

Patients with CAD, Mitral valve rheumatic heart disease, or lupus Caution with: Tartrazine hypersensitivity (common in those who have aspirin hypersensitivity)

IV push dose:

Common Adult initial dose: 5-10 mg IV Textbook adult: 0.1 – 0.2 mg/kg IV every 20-60 minutes Textbook Pediatric: 0.1 – 0.2 mg/kg IV every 4-6 hours. Maximum dose: 20 mg

Method of Action:

DIRECT Guanylate cyclase agonist; ARTERIOLAR dilation with subsequent baroreceptor reflex which increases HR Dilation is more prevalent in coronary, cerebral, renal, and splanchnic arteries. Activates the RAAS system as well (which is working against the therapeutic effect). For the RAAS activation, those who regularly take hydralazine, there is usually a beta blocker and diuretic to counteract the effects 90% protein bound.

Metabolism:

Extensive Hepatic

Reference

Barash. Clinical anesthesia. 7th edition. 2013.
Nagelhout. Nurse anesthesia. 5th edition. 2014.
Khalil H, Zeltser R. Hydralazine. StatPearls. Updated 2023.link
Hydralazine. OpenAnesthesia. 2023.link
Hydralazine Dosage Guide. Drugs.com. 2025.link
IWK Health Centre Pediatric Drug Dosing Guidelines: Hydralazine (IV/IM 0.1-0.2 mg/kg/dose q4-6h; max 20 mg/dose).link