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Hydroxyurea (Oral)

Prior to Initiation of Therapy

  • Treatment of patients with Droxia (hydroxyurea capsules, USP) may be complicated by severe, sometimes life-threatening, adverse effects. Droxia should be administered under the supervision of a physician experienced in the use of this medication for the treatment of sickle cell anemia.
  • Hydroxyurea is mutagenic and clastogenic, and causes cellular transformation to a tumorigenic phenotype. Hydroxyurea is thus unequivocally genotoxic and a presumed transspecies carcinogen that implies a carcinogenic risk to humans. In patients receiving long-term hydroxyurea for myeloproliferative disorders, such as polycythemia vera and thrombocythemia, secondary leukemias have been reported. It is unknown whether this leukemogenic effect is secondary to hydroxyurea or is associated with the patients' underlying disease. The physician and patient must very carefully consider the potential benefits of Droxia relative to the undefined risk of developing secondary malignancies.


  • Hydroxyurea is a cytotoxic and myelosuppressive agent and requires close supervision. Some patients treated at the recommended initial dose of 15 mg/kg/day have experienced severe or life threatening myelosuppression, requiring interruption of treatment and dose reduction.
  • This drug should not be given initially or therapy should be stopped if bone marrow function is markedly depressed (neutrophils below 2000 cells/mm3, a platelet count below 80,000/mm3, a hemoglobin level below 4.5 g/dL, or reticulocytes below 80,000/mm3 when the hemoglobin concentration is below 9 g/dL. Reinitiation of therapy should follow product insert guidelines. (See product insert for more details under WARNINGS. )

Patient Counseling Information




Medication Guides

Patient Medication Guide - Droxia

Patient Medication Guide - HYDREA

Patient Medication Guide - Siklos

Package Inserts


Additional Information

Updated January 2018