Direct arteriolar vasodilator
ATC code: C02DB02 (Hydralazine)
Direct arteriolar smooth muscle relaxation via interference with calcium metabolism and potassium channel activation. Lowers peripheral resistance, reflexively increases heart rate and cardiac output. Acts mainly on arteries, not veins. Short T½ 3-7 h.
First line
Hypertensive emergency and preeclampsia. Per 222 (2020), NG133 2019, SEGO 2023 – IV agent for acute severe BP elevation in pregnancy (≥160/110). Dose 5-10 mg IV slowly, repeated every 20-30 min until BP control (max 30 mg). Alternative – IV labetalol. Not recommended for chronic oral BP control due to tachycardia and lupus-like syndrome.
Third line
Hydralazine during breastfeeding. RID 1.2%, Hale L2. Acceptable but not first-line due to maternal reflex tachycardia and lupus-like syndrome risk with chronic use. Prefer enalapril, methyldopa, labetalol.
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Use as indicated for crisis control in any trimester.
Compatible. Hale L2. RID 1.2%. Not first-line due to maternal tachycardia.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Hydralazine is evaluated for the following indications with varying evidence strength: Hypertension in pregnancy (evidence tier A), Hypertension during breastfeeding (evidence tier B). See the full indication matrix with dosing and citations above on this page.
Common side effects of Hydralazine (≥ 1 in 100): Tachycardia, Headache, Flushing, Orthostatic hypotension, Nausea. See the Safety section for uncommon and serious reactions.
FDA category C. Use as indicated for crisis control in any trimester.
Compatible. Hale L2. RID 1.2%. Not first-line due to maternal tachycardia.
Hydralazine is contraindicated in: Hypersensitivity; CHD, tachyarrhythmias; Aortic aneurysm; Severe hepatic impairment; Systemic lupus erythematosus. Full list in the Safety section.