What are the side effects of hydralazine?

Side Effects of Hydralazine

Hydralazine is associated with several significant side effects including reflex tachycardia, sodium and water retention, headache, palpitations, and drug-induced lupus-like syndrome at higher doses. 1

Common Side Effects

Cardiovascular Effects

• Reflex tachycardia - occurs due to vasodilation and activation of the sympathetic nervous system 1, 2
• Sodium and water retention - requires concurrent use of a diuretic 1
• Hypotension - especially in elderly patients 2
• Palpitations 3
• Anginal attacks - due to myocardial stimulation 3
• ECG changes of myocardial ischemia 3

Neurological Effects

• Headache - common extension of the pharmacologic effect 2, 3
• Dizziness 2, 3
• Peripheral neuritis - evidenced by paresthesia, numbness, and tingling 3

Gastrointestinal Effects

• Nausea 3
• Vomiting 2
• Gastrointestinal complaints 2

Serious Adverse Effects

Autoimmune Reactions

• Drug-induced lupus-like syndrome - most significant at doses >100mg daily 1, 4
  • Risk factors include: high daily doses, slow acetylator phenotype, HLA-DRw4 phenotype, therapy longer than 3 months, and female gender 4
  • Characterized by arthralgia, fever, chest pain, and malaise 3
  • Requires immediate discontinuation of the drug 4

Hematologic Effects

• Blood dyscrasias - including reduction in hemoglobin, leukopenia, agranulocytosis, and purpura 3
• Hemolytic anemia 5

Renal and Vascular Effects

• Vasculitis - including ANCA-associated vasculitis 6
• Glomerulonephritis 5

Hepatic Effects

• Liver injury - presenting with hepatocellular injury pattern 7
• Hepatic steatosis - as observed in liver biopsies 7

Monitoring Recommendations

1. Baseline assessment:

   • Complete blood count
   • Antinuclear antibody titer determination
   • Liver function tests 3, 4

2. Ongoing monitoring:

   • Regular blood pressure monitoring, especially during initial administration 2
   • Periodic complete blood counts and antinuclear antibody titers during prolonged therapy 3
   • Monitor for signs and symptoms of lupus-like syndrome at each visit 4
   • Consider liver enzyme monitoring throughout treatment course 7

Precautions and Contraindications

• Use with caution in patients with:

  • Suspected coronary artery disease
  • Mitral valvular disease
  • Cerebrovascular accidents
  • Advanced renal damage 3

• Drug interactions:

  • MAO inhibitors should be used with caution
  • Potent parenteral antihypertensive drugs (e.g., diazoxide) may cause profound hypotension when used with hydralazine 3

Management of Side Effects

• For reflex tachycardia and fluid retention: combine with a beta-blocker and diuretic 1
• For lupus-like syndrome: immediate discontinuation of hydralazine 4
• For blood dyscrasias: discontinue therapy 3
• For liver injury: discontinuation typically leads to normalization of liver enzymes 7

Careful patient selection, appropriate dosing, and vigilant monitoring are essential to minimize the risk of serious adverse effects with hydralazine therapy.