Pharm

Hydralazine

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Hydralazine, Apresoline, BiDil

  • See Also
  1. Direct Acting Vasodilator
  2. Intravenous Antihypertensive
  3. Nitroprusside
  4. Fenoldopam
  • Indications
  1. Hypertension
  2. Congestive Heart Failure
  3. Pregnancy Induced Hypertension (Preeclampsia)
  • Contraindications
  1. Ischemic Heart Disease (Hydralazine provokes Angina)
  • Mechanism
  1. Arteriole dilation (independent of sympathetic drive)
  2. Decreases Blood Pressure with compensatory reflex Tachycardia
  3. Increases Cardiac Output and renal Blood Flow
  • Dosing
  • Hydralazine (Adults)
  1. Hypertensive Emergency
    1. Hydralazine: 10-20 mg IV (or 10 to 50 mg IM) every 4 to 6 hours as needed
  2. Pregnancy Induced Hypertension (Preeclampsia)
    1. Start: 5 mg IV (or 10 mg IM) every 20 minutes prn
    2. Maintenance: 5 to 10 mg IV (or 10 mg to 20 mg IM) every 3 hours prn
  3. Hypertension
    1. Start 10 mg orally taken 2 to 4 times daily for 3-4 days
    2. Next 25 mg orally take 2 to 4 times daily
    3. Titrate as needed to 50 mg orally 2 to 4 times daily
    4. Maximum: 300 mg/day
    5. Renal Adjustment
      1. GFR 10 to 50 ml/min: Decrease dosing frequency to every 8 hours
      2. GFR <10 ml/min: Decrease dosing frequency to every 8 to 16 hours (up to every 24 hours)
  4. Congestive Heart Failure
    1. Start 10 to 25 mg orally three times daily
    2. Target 75 mg orally three times daily
    3. Maximum 100 mg orally three times daily
    4. Often combined with Isosorbide (see BiDil below)
  • Dosing
  • Hydralazine (Children, not FDA approved)
  1. Hypertensive Urgency or Emergency
    1. Start 0.1 to 0.2 mg/kg (up to 20 mg) IV or IM every 4 to 6 hours as needed
  2. Hypertension
    1. Start 0.75 to 1 mg/kg/day orally divided 2 to 4 times daily
    2. May titrate over the next month up to 7.5 mg mg/kg/day divided 2 to 4 times daily (up to 25 mg/dose)
  • Dosing
  • Hydralazine Combinations
  1. Hydralazine with Isosorbide Dinitrate 37.5/20 (BiDil)
    1. Dose: 1-2 tablets orally three times daily
    2. Indicated Class III CHF patients (esp. African American)
    3. Very expensive: $400/month (Generic Drugs separately are $60/month)
  • Adverse Effects
  1. Headache
  2. Palpitations
  3. Reflex Tachycardia
    1. Includes Fetal Tachycardia (in Preeclampsia)
    2. Beta Blockers are often used in combination with Beta Blockers to counter reflex Tachycardia
  4. Leg Edema
    1. Due to reflex Sodium and water retention
    2. Diuretics are often combined with Hydralazine
  5. Dizziness
  6. Nausea
  7. Nasal Congestion
  8. Hepatitis
  9. Angina (in pre-existing Ischemic Heart Disease)
  10. Systemic Lupus Erythematosus Like Syndrome
  11. Peripheral Neuritis
    1. Hydralazine interferes with Vitamin B6 metabolism in neural tissue
  • Safety
  1. Pregnancy Category C
  2. Considered safe in Lactation
  • Metabolism
  1. Excreted unchanged as well as with acetylated metabolites
  2. Lower serum levels in rapid acetylators
  • Resources
  1. Hydralazine IV (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e31239e0-8c5a-4d10-9404-af32278484a3
  2. Hydralazine Oral Tablet (Dailymed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a04eefaf-ba3c-448d-8ece-4aa9ab2e3508
  • References
  1. (2020) Med Lett Drugs Ther 62(1598): 73-80
  2. Olson (2020) Clinical Pharmacology, Medmaster Miami, p. 66-7
  3. Hamilton (2020) Tarascon Pocket Pharmacopoeia