Hydrea (hydroxyurea) is an oral antineoplastic and antimetabolite medication primarily indicated for the management of certain chronic myeloproliferative disorders, including polycythemia vera, essential thrombocythemia, and chronic myeloid leukemia. It functions as a ribonucleotide reductase inhibitor, effectively reducing the overproduction of blood cells by interfering with DNA synthesis without directly breaking the DNA strand. This mechanism offers a targeted approach to controlling hematological parameters, thereby reducing the risk of thrombotic events and disease progression. Its well-established efficacy and manageable safety profile have made it a cornerstone in hematologic therapy for decades.

Features

• Active Ingredient: Hydroxyurea
• Available Formulations: 500 mg capsules
• Pharmacologic Class: Antimetabolite, Antineoplastic Agent
• Mechanism of Action: Inhibition of ribonucleotide reductase, leading to S-phase cell cycle arrest
• Bioavailability: Rapid and nearly complete oral absorption
• Half-life: Approximately 3–4 hours
• Metabolism: Hepatic and intracellular
• Excretion: Primarily renal

Benefits

• Effectively reduces elevated hematocrit, platelet, and white blood cell counts in myeloproliferative neoplasms
• Decreases the risk of thrombotic complications such as stroke, myocardial infarction, and venous thromboembolism
• May reduce splenomegaly and associated symptoms in certain conditions
• Can serve as an alternative or bridge therapy to interferon in patients who are not candidates for more aggressive treatment
• Oral administration allows for convenient outpatient management
• Cost-effective compared to many newer biologic agents

Common use

Hydrea is predominantly prescribed for the treatment of polycythemia vera and essential thrombocythemia to maintain hematocrit below 45% and control thrombocytosis, respectively. It is also used in chronic myeloid leukemia, particularly in the chronic phase, when tyrosine kinase inhibitors are not suitable or available. Off-label uses include management of sickle cell disease to reduce the frequency of painful crises and transfusion requirements, and as a radiosensitizer in certain head and neck cancers.

Dosage and direction

Dosage must be individualized based on patient weight, hematological parameters, and tolerance. For polycythemia vera and thrombocythemia, the initial dose is typically 15–20 mg/kg/day as a single daily dose. Regular monitoring of complete blood counts is essential, with dosage adjustments made to achieve target hematological values while avoiding myelosuppression. Capsules should be swallowed whole with water; if unable to swallow, the contents may be emptied into water and consumed immediately. Administration after food may minimize gastrointestinal upset.

Precautions

Hydrea is a cytotoxic agent and should be handled with appropriate precautions. Healthcare providers should wear gloves when handling the medication. Patients must be advised to avoid pregnancy and use effective contraception during treatment and for at least 6 months after discontinuation. Regular monitoring of renal and hepatic function is recommended. Due to its mechanism, Hydrea may mask dermatological inflammation; careful skin examination should be performed regularly. Vaccination with live vaccines should be avoided during therapy.

Contraindications

Hydrea is contraindicated in patients with severe bone marrow suppression (evidenced by leukopenia, thrombocytopenia, or anemia), severe renal impairment (creatinine clearance <30 mL/min), and known hypersensitivity to hydroxyurea or any component of the formulation. It should not be used during pregnancy unless the potential benefit justifies the potential risk to the fetus.

Possible side effect

• Myelosuppression: Anemia, leukopenia, thrombocytopenia (dose-related and usually reversible)
• Gastrointestinal: Nausea, vomiting, diarrhea, constipation, stomatitis
• Dermatological: Maculopapular rash, skin ulceration, hyperpigmentation, alopecia
• Neurological: Dizziness, headache
• Hepatic: Elevated liver enzymes (rare)
• Renal: Elevated serum creatinine (rare)
• Other: Fever, malaise, disorientation

Drug interaction

• Live vaccines: Increased risk of vaccine-induced infection
• Other myelosuppressive agents: Additive bone marrow toxicity
• Didanosine: Increased risk of pancreatitis and neuropathy
• Interferon-alpha: Potential synergistic effects, requiring careful monitoring
• Antiretroviral drugs: Altered pharmacokinetics possible

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is nearly time for the next dose. Doubling the dose to make up for a missed dose is not recommended. Patients should contact their healthcare provider for specific guidance based on their treatment schedule.

Overdose

Acute overdose may manifest as exacerbated myelosuppression, mucositis, nausea, vomiting, and dermatological toxicity. Management is supportive and includes hematological monitoring, transfusions if indicated, and symptomatic treatment. There is no specific antidote; hemodialysis may be considered due to partial renal excretion.

Storage

Store at room temperature (15–30°C or 59–86°F) in a tightly closed container, protected from moisture and light. Keep out of reach of children and pets. Do not use after the expiration date printed on the packaging.

Disclaimer

This information is intended for educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for personalized recommendations. Dosage and indications may vary based on regional prescribing information and individual patient factors.

Reviews

Clinical studies and long-term observational data consistently demonstrate Hydrea’s efficacy in controlling blood counts and reducing thrombotic risk in myeloproliferative disorders. Many hematologists regard it as a reliable first-line option for patients who are not candidates for interferon therapy. Patient-reported outcomes often note improvement in symptoms related to hyperviscosity, though some report gastrointestinal side effects or skin changes. Adherence is generally high due to once-daily dosing.