II. Indications
III. Contraindications
- Ischemic Heart Disease (Hydralazine provokes Angina)
IV. Mechanism
- Arteriole dilation (independent of sympathetic drive)
- Decreases Blood Pressure with compensatory reflex Tachycardia
- Increases Cardiac Output and renal Blood Flow
V. Dosing: Hydralazine (Adults)
-
Hypertensive Emergency
- Hydralazine: 10-20 mg IV (or 10 to 50 mg IM) every 4 to 6 hours as needed
-
Pregnancy Induced Hypertension (Preeclampsia)
- Start: 5 mg IV (or 10 mg IM) every 20 minutes prn
- Maintenance: 5 to 10 mg IV (or 10 mg to 20 mg IM) every 3 hours prn
-
Hypertension
- Start 10 mg orally taken 2 to 4 times daily for 3-4 days
- Next 25 mg orally take 2 to 4 times daily
- Titrate as needed to 50 mg orally 2 to 4 times daily
- Maximum: 300 mg/day
- Renal Adjustment
- GFR 10 to 50 ml/min: Decrease dosing frequency to every 8 hours
- GFR <10 ml/min: Decrease dosing frequency to every 8 to 16 hours (up to every 24 hours)
-
Congestive Heart Failure
- Start 10 to 25 mg orally three times daily
- Target 75 mg orally three times daily
- Maximum 100 mg orally three times daily
- Often combined with Isosorbide (see BiDil below)
VI. Dosing: Hydralazine (Children, not FDA approved)
-
Hypertensive Urgency or Emergency
- Start 0.1 to 0.2 mg/kg (up to 20 mg) IV or IM every 4 to 6 hours as needed
-
Hypertension
- Start 0.75 to 1 mg/kg/day orally divided 2 to 4 times daily
- 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)
VII. Dosing: Hydralazine Combinations
- Hydralazine with Isosorbide Dinitrate 37.5/20 (BiDil)
- Dose: 1-2 tablets orally three times daily
- Indicated Class III CHF patients (esp. African American)
- Very expensive: $400/month (Generic Drugs separately are $60/month)
VIII. Adverse Effects
- Headache
- Palpitations
- Reflex Tachycardia
- Includes Fetal Tachycardia (in Preeclampsia)
- Beta Blockers are often used in combination with Beta Blockers to counter reflex Tachycardia
- Leg Edema
- Dizziness
- Nausea
- Nasal Congestion
- Hepatitis
- Angina (in pre-existing Ischemic Heart Disease)
- Systemic Lupus Erythematosus Like Syndrome
- Peripheral Neuritis
- Hydralazine interferes with Vitamin B6 metabolism in neural tissue
IX. Safety
- Pregnancy Category C
- Considered safe in Lactation
X. Metabolism
- Excreted unchanged as well as with acetylated metabolites
- Lower serum levels in rapid acetylators
XI. Resources
- Hydralazine IV (DailyMed)
- Hydralazine Oral Tablet (Dailymed)
XII. References
- (2020) Med Lett Drugs Ther 62(1598): 73-80
- Olson (2020) Clinical Pharmacology, Medmaster Miami, p. 66-7
- Hamilton (2020) Tarascon Pocket Pharmacopoeia
Images: Related links to external sites (from Bing)
Related Studies
| hydralazine (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
| HYDRALAZINE 10 MG TABLET | Generic | $0.03 each |
| HYDRALAZINE 100 MG TABLET | Generic | $0.08 each |
| HYDRALAZINE 25 MG TABLET | Generic | $0.04 each |
| HYDRALAZINE 50 MG TABLET | Generic | $0.05 each |
| bidil (on 10/1/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
| BIDIL 20 MG-37.5 MG TABLET | Generic | $1.58 each |