Hydralazine

Class: Direct-acting vasodilator Route of administration: Oral, Intravenous Main indications:

• Hypertension (especially in pregnancy-related hypertensive emergencies)
• Congestive heart failure (often combined with nitrates)

Hydralazine causes direct relaxation of arteriolar smooth muscle, leading to arteriolar vasodilation (with minimal venous effect). This reduces peripheral vascular resistance and lowers systemic blood pressure.

Oral:

• Initial: 25 mg two to four times daily
• Maintenance: 100–200 mg/day in divided doses

Intravenous (emergency use):

• Typically 10–20 mg IV every 4–6 hours as needed

• Reflex tachycardia
• Fluid retention and edema
• Drug-induced lupus-like syndrome (especially with doses >200 mg/day)
• Headache, flushing, nausea
• Postural hypotension

• Coronary artery disease (active ischemia)
• Aortic dissection
• Hypersensitivity to hydralazine

• Blood pressure and heart rate
• Renal function and electrolytes
• Antinuclear antibodies (ANA) in long-term therapy to monitor for lupus

• Often combined with beta-blockers and diuretics to counteract reflex tachycardia and fluid retention
• Considered safe during pregnancy