Hydroxyurea

What it is and how it works

Mechanism of Action The precise mechanism by which hydroxyurea produces its cytotoxic and cytoreductive effects is not known. However, various studies support the hypothesis that hydroxyurea causes an immediate inhibition of DNA synthesis by acting as a ribonucleotide reductase inhibitor, without interfering with the synthesis of ribonucleic acid or of protein. The mechanisms by which XROMI produces its beneficial effects in patients with sickle cell anemia are uncertain.

Indications

is indicated to reduce the frequency of painful crises and reduce the need for blood transfusions in pediatric patients aged 6 months of age and older with sickle cell anemia with recurrent moderate to severe painful crises. XROMI is an antimetabolite indicated to reduce the frequency of painful crises and reduce the need for blood transfusions in pediatric patients aged 6 months of age and older with sickle cell anemia with recurrent moderate to severe painful crises.

Dosage and administration (summary)

Initial dose: 15 mg/kg orally once daily. Monitor the patient’s blood count every two weeks. The dose may be increased by 5 mg/kg/day every 8 to 12 weeks until a maximum tolerated dose or 35 mg/kg/day is reached if blood counts are in an acceptable range. The dose is not increased if blood counts are below the acceptable range and toxic. Discontinue XROMI until hematologic recovery if blood counts are considered toxic. Treatment may be resumed after reducing the dose by 2.5mg/kg/day to 5mg/kg/day from the dose associated with hematological toxicity. Renal impairment: Reduce the dose of XROMI by 50% in patients with creatinine clearance less than 60 mL/min.

Contraindications

is contraindicated in patients: who have demonstrated a previous hypersensitivity to hydroxyurea or any other component of its formulation. . In patients who have demonstrated a previous hypersensitivity to hydroxyurea or any other component of its formulation.

Warnings and precautions

Hemolytic anemia: Monitor blood counts throughout treatment. If hemolysis persists, discontinue XROMI. Embryo-Fetal toxicity: Can cause fetal harm. Advise of potential risk to a fetus and use of effective contraception. ( 5.4 , 8.1 , 8.3) Vasculitic toxicities: Institute treatment and discontinue XROMI if this occurs. Live Vaccinations: Avoid live vaccine use in a patient taking XROMI. Risks with concomitant use of antiretroviral drugs: Pancreatitis, hepatotoxicity, and neuropathy have occurred. Monitor for signs and symptoms in patients with HIV infection using antiretroviral drugs.

Pregnancy

Pregnancy Risk Summary XROMI can cause fetal harm based on findings from animal studies and the drug’s mechanism of action . There are no data with XROMI use in pregnant women to inform a drug-associated risk.

Storage and supply

Storage Store XROMI between 2°C to 8°C (35°F to 46°F) excursions permitted to 25°C (77°F) for up to 72 hours. Keep the bottle tightly closed to protect the integrity of the product and minimize the risk of accidental spillage. Do not freeze. Use within 12 weeks after initially opening the bottle.

Source: Hydroxyurea (Xromi) — US FDA prescribing information, 2026-02-02, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.