hydroxyurea

Hydroxyurea is an antineoplastic and antimetabolite medication used to treat certain cancers and hematologic disorders, and to reduce complications of sickle cell disease. It acts as a ribonucleotide reductase inhibitor, decreasing the synthesis of deoxyribonucleotides and thereby inhibiting DNA replication in rapidly dividing cells. As a result, it lowers counts of leukocytes and platelets and can slow progression of malignant clones.

Indications include myeloproliferative neoplasms such as polycythemia vera and essential thrombocythemia, and certain leukemias and solid tumors in combination regimens. It is also used in sickle cell disease to increase fetal hemoglobin (HbF) and reduce vaso-occlusive crises.

Administration is oral, available as capsules or a liquid. Dosing is individualized and requires frequent monitoring for myelosuppression; treatment often begins in a controlled setting with gradual adjustment and ongoing outpatient follow-up.

Side effects and risks include cytopenias (neutropenia and thrombocytopenia), fatigue, gastrointestinal upset, stomatitis, rash, alopecia, nail changes, mucosal ulcers, and liver enzyme elevation. Long-term use has been associated with risk of secondary malignancies and ongoing cytopenias. Renal impairment can affect clearance. Caution in pregnancy; hydroxyurea is teratogenic and contraindicated in pregnancy and breastfeeding. Both men and women should use effective contraception during treatment. Interactions with other myelosuppressive drugs can increase toxicity.

Monitoring typically includes weekly complete blood counts at start, then periodic evaluation of liver and kidney function, uric acid, and assessment for mucositis and infection. Brand names include Hydrea and Droxia.