What is the recommended dose of hydrazine for treating hypertension?

Hydralazine Dosing for Hypertension

For hypertension treatment, oral hydralazine is recommended at a dose of 100-200 mg daily divided into 2 or 3 doses, with a maximum of 200 mg per day. 1

Oral Hydralazine for Chronic Hypertension

Hydralazine is classified as a direct vasodilator and is considered a secondary agent for hypertension management, not a first-line therapy. The dosing recommendations are:

• Initial dose: Start with lower doses and titrate up
• Usual dose range: 100-200 mg daily 1
• Dosing frequency: Divided into 2-3 doses per day 1
• Maximum daily dose: 200 mg 1

Intravenous Hydralazine for Hypertensive Emergencies

For hypertensive emergencies requiring IV therapy:

• Initial dose: 10 mg via slow IV infusion (maximum initial dose 20 mg) 1
• Repeat dosing: Every 4-6 hours as needed 1
• Onset of action: Blood pressure begins to decrease within 10-30 minutes 1
• Duration of effect: The blood pressure-lowering effect lasts 2-4 hours 1

Important Clinical Considerations

Limitations and Cautions

1. Not a first-line agent: Hydralazine is generally reserved as a secondary agent for hypertension 1

2. Unpredictable response: The unpredictability of response and prolonged duration of action make hydralazine less desirable as a first-line agent for acute treatment in most patients 1

3. Associated adverse effects:

   • Sodium and water retention
   • Reflex tachycardia
   • Drug-induced lupus-like syndrome at higher doses 1

4. Combination therapy: Should be used with a diuretic and beta-blocker to counteract reflex tachycardia and fluid retention 1

Place in Therapy

Hydralazine is recommended as a step 3 or 4 agent in hypertension management:

• For resistant hypertension when first-line therapies fail 1
• In heart failure patients with persistent hypertension despite ACE inhibitor/ARB, beta-blocker, MRA, and diuretic therapy 1

Special Populations

For patients with heart failure and hypertension, hydralazine (often combined with isosorbide dinitrate) can be particularly useful:

• Fixed-dose combination: 20 mg isosorbide dinitrate/37.5 mg hydralazine TID, up to 40 mg/75 mg TID 1
• Used as part of a stepped approach to managing hypertension in heart failure patients 1

Algorithm for Hydralazine Use in Hypertension

1. First: Optimize first-line agents (ACE inhibitors/ARBs, calcium channel blockers, thiazide diuretics)
2. Second: Add beta-blocker if not contraindicated
3. Third: Consider hydralazine if BP remains uncontrolled
   • Start at lower dose (25-50 mg BID or TID)
   • Titrate to effective dose (up to 100-200 mg daily)
   • Always combine with a diuretic to prevent fluid retention
   • Consider adding a beta-blocker if not already prescribed to prevent reflex tachycardia

Remember that hydralazine is not recommended as monotherapy for hypertension and should be part of a comprehensive treatment regimen that includes first-line agents.