Clinical properties of hydroxyurea

Characteristic	Hydroxyurea
Drug class	Antimetabolite
Mechanism of action	Not genotoxic, impairs DNA repair by inhibiting ribonucleotide reductase, increases HbF production
Specificity	Affects all cell lines
Pharmacology	Half-life 4 hours; 40% renally excreted, 60% metabolized
Starting dose	15 to 20 mg/kg per day orally for routine treatment of MPNs or sickle cell disease; 50 to 100 mg/kg per day orally for treatment of hyperleukocytosis
Onset of action	3 to 5 days for routine treatment of MPNs; weeks, up to 6 months, for treatment of sickle cell disease; 1 to 2 days for hyperleukocytosis
Side effects observed in >10% of patients	Neutropenia, anemia, oral ulcers, mild gastrointestinal upset, hyperpigmentation, rash, nail changes
Side effects observed in ≤10% of patients	Ankle ulcers, lichen planus-like lesions of the mouth and skin, nausea, diarrhea
Rare side effects	Fever, liver function test abnormalities
Contraindications	Severe bone marrow suppression (eg, neutropenia, thrombocytopenia); pregnancy, attempted conception, breast feeding

Refer to UpToDate topics on specific indications for additional details about administration, monitoring, and adverse effects.

MPN: myeloproliferative neoplasm; HbF: fetal hemoglobin.

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