Hydroxyurea Dosing and Monitoring for Sickle Cell Disease

Initial Dosing and Administration

Hydroxyurea is taken once daily orally and is available as capsules, fast-dissolving tablets, or compounded liquid formulations, according to the American Academy of Pediatrics 1
Children as young as 9 months of age with HbSS or Sβ0-thalassemia should be offered hydroxyurea even without clinical symptoms, as recommended by the American Academy of Pediatrics 1, 4

Complete blood count (CBC) with reticulocyte count should be monitored every 2-4 weeks during initial dose titration and every 1-3 months once on stable dose, depending on duration of therapy and dose stability, as suggested by the American Academy of Pediatrics 1
Dose-limiting toxicity is primarily myelosuppression, which typically resolves within 2 weeks of temporary discontinuation, according to the American Thoracic Society 2, 3
After temporary discontinuation due to toxicity, therapy can be resumed at a lower dose, as recommended by the American Thoracic Society 2

For patients with sickle cell disease and chronic kidney disease with worsening anemia, combination therapy with erythropoiesis-stimulating agents may allow for more aggressive hydroxyurea dosing, although this is based on a guideline from Praxis Medical Insights, a non-preferred source, it is still notable that when using combination therapy with erythropoiesis-stimulating agents, hemoglobin levels should not exceed 10 g/dL to reduce risk of vaso-occlusive complications 5

Myelosuppression is the most common adverse effect but is typically manageable with dose adjustments, as noted by the American Thoracic Society 2, 3
Adherence to medication and monitoring schedule is critical for achieving optimal outcomes, according to the American Academy of Pediatrics 1
Hydroxyurea is not associated with increased risk of birth defects, infection, stroke, or neoplasia in long-term follow-up studies, as reported by the American Thoracic Society 2, 3