What is the recommended dosage of hydralazine (Hydralazine) for treating hypertension (high blood pressure) and heart failure?

Hydralazine Dosage for Hypertension and Heart Failure

For hypertension, hydralazine should be initiated at 10 mg four times daily for the first 2-4 days, increased to 25 mg four times daily for the remainder of the first week, then to 50 mg four times daily for maintenance, with a maximum daily dose of 300 mg in resistant cases. 1

Dosing for Hypertension

Initial Dosing and Titration

• Start with 10 mg four times daily for the first 2-4 days
• Increase to 25 mg four times daily for the remainder of the first week
• For the second week and beyond, increase to 50 mg four times daily
• Adjust to the lowest effective maintenance dose 1
• For resistant hypertension, doses may be increased up to 300 mg daily, though this increases risk of adverse effects 1, 2

Alternative Dosing Schedules

• For better adherence, the American Heart Association suggests that hydralazine can be administered as 10-25 mg three times daily initially, with increases of 10 mg per dose as needed 2
• Target doses for resistant hypertension may reach up to 75 mg three times daily 2

Dosing for Heart Failure

Fixed-Dose Combination with Isosorbide Dinitrate

• Initial dose: 20 mg isosorbide dinitrate/37.5 mg hydralazine three times daily 3
• Maximum dose: 40 mg isosorbide dinitrate/75 mg hydralazine three times daily 3
• Mean dose achieved in clinical trials: 90 mg isosorbide dinitrate/175 mg hydralazine daily 3

Separate Administration

• Initial dose: 20-30 mg isosorbide dinitrate/25-50 mg hydralazine three times daily or once daily 3
• Maximum dose: 40 mg isosorbide dinitrate three times daily (with appropriate hydralazine dosing) 3

Special Considerations

Combination Therapy

• For hypertension, consider combining with a thiazide diuretic and/or beta-blocker to minimize reflex tachycardia and fluid retention 2, 1
• In heart failure, hydralazine is typically combined with isosorbide dinitrate, particularly beneficial in self-identified Black patients 2

Dose Adjustments

• Elderly patients may require lower doses due to increased sensitivity 2
• Patients with renal impairment may need extended dosing intervals, as the duration of action is longer in patients with creatinine clearance <35 ml/min (14.3 ± 1.4 hours vs 7.9 ± 0.5 hours in those with adequate renal function) 4

Monitoring

• Blood pressure should be monitored after each dose increase 2
• Watch for symptomatic hypotension (dizziness, lightheadedness) 2
• Monitor for common side effects: reflex tachycardia, sodium/water retention, headache, flushing, and vomiting 2
• Be aware that long-term use at higher doses (>100 mg daily) increases risk of drug-induced lupus-like syndrome 2

Intravenous Administration (for Hypertensive Emergencies)

• Initial dose: 10 mg via slow IV infusion (maximum initial dose 20 mg) 2
• Can be repeated every 4-6 hours as needed 2
• When converting from oral to IV, use a 2:1 ratio (oral:IV) 2
• Continuous blood pressure monitoring is recommended during initial administration 2

By following these dosing guidelines and monitoring protocols, hydralazine can be effectively used to manage both hypertension and heart failure while minimizing adverse effects.