Hydralazine lowers blood pressure primarily through:

• Peripheral vasodilation: Directly relaxes vascular smooth muscle.

• Calcium interference: Alters calcium metabolism in muscle cells.

• Hemodynamic effects:

  • Decreases peripheral resistance and diastolic pressure.

  • Increases heart rate, stroke volume, and cardiac output.

  • May raise plasma renin, aldosterone, and sodium retention.

• Bioavailability:

  • Rapid oral absorption.

  • Peak plasma: 1–2 hours.

  • Half-life: 3–7 hours.

  • 87% plasma protein binding.

  • Metabolized in liver; excreted via urine.

Treatment of essential hypertension, either alone or as adjunct therapy.

10 mg four times daily

Common: Headache, nausea, vomiting, diarrhea, palpitations, tachycardia

Less Frequent:

Cardiovascular: Edema, hypotension

Neurologic: Neuritis, depression, anxiety

Hematologic: Anemia, leukopenia, agranulocytosis

Hypersensitivity: Rash, fever, hepatitis (rare)

Contraindications

• Hypersensitivity to hydralazine
• Coronary artery disease
• Rheumatic heart disease affecting the mitral valve

Warnings & Precautions

• Lupus-like syndrome: Can occur and may require discontinuation or steroid treatment.
• Cardiac risks: May induce angina, ischemia, or myocardial infarction in predisposed individuals.
• Neurologic side effects: Includes dizziness, tremors, and rarely, psychosis.
• Renal caution: Use with care in patients with advanced kidney disease.
• Pregnancy: Category C – potential teratogenic effects in animals.
• Pediatric use: Dosing is weight-based, up to 7.5 mg/kg or max 200 mg/day.