Hydrea (hydroxyurea) is an oral chemotherapeutic agent specifically formulated for the management of certain chronic blood cell disorders. It belongs to the class of antimetabolites and functions as a ribonucleotide reductase inhibitor, effectively modulating the overproduction of abnormal blood cells. This medication is a cornerstone in the treatment of specific myeloproliferative neoplasms, offering a targeted approach to reduce complications and improve hematological parameters. Its well-established efficacy profile and oral administration make it a fundamental option in specialized hematology practice.

Features

• Active Pharmaceutical Ingredient: Hydroxyurea
• Standard Dosage Form: Hard gelatin capsules (200 mg, 300 mg, 400 mg, 500 mg)
• Pharmacologic Class: Antimetabolite, Ribonucleotide reductase inhibitor
• Administration Route: Oral
• Prescription Status: Rx-only, requiring close medical supervision
• Mechanism of Action: Inhibits the synthesis of DNA without interfering with the synthesis of RNA or protein

Benefits

• Effectively reduces high platelet and white blood cell counts, decreasing the risk of thrombotic and hemorrhagic events.
• Alleviates disease-related symptoms such as splenomegaly (enlarged spleen), pruritus (itching), and bone pain.
• Can reduce the need for frequent phlebotomy in certain conditions by controlling hematocrit levels.
• Demonstrates a predictable response profile, allowing for tailored dose titration based on individual patient blood counts.
• Oral administration facilitates outpatient management and improves patient compliance compared to intravenous therapies.
• Well-documented long-term safety and efficacy data from decades of clinical use.

Common use

Hydrea is primarily indicated for the treatment of specific chronic myeloproliferative disorders. Its most common and well-established use is in the management of polycythemia vera, particularly in patients who are at high risk for thrombosis or who have had an inadequate response to phlebotomy alone. It is also a standard therapy for essential thrombocythemia, especially in high-risk patients (e.g., those with a history of thrombosis, age over 60, or extreme platelet counts) to reduce the risk of thrombotic complications. Furthermore, it is used in the treatment of certain cases of chronic myeloid leukemia, particularly in the chronic phase, and for managing sickle cell anemia by increasing the production of fetal hemoglobin, which reduces the frequency of painful crises and the need for blood transfusions. Its use is always initiated and monitored by a hematologist or oncologist.

Dosage and direction

Dosage is highly individualized based on the specific condition being treated, the patient’s body weight, and their hematological response and tolerance. Therapy must be initiated under the supervision of a physician experienced in the use of chemotherapeutic agents.

• Polycythemia Vera & Essential Thrombocythemia: The initial dose typically ranges from 15 to 20 mg per kilogram of body weight per day, administered as a single daily dose. Continuous daily therapy is required for a suppressive effect on bone marrow. Dosage is adjusted based on weekly blood count monitoring until a stable maintenance dose is achieved.
• Sickle Cell Anemia: The initial recommended dose is 15 mg per kilogram per day as a single dose. This may be increased by 5 mg per kilogram per day every 12 weeks until the maximum tolerated dose (up to 35 mg/kg/day) is reached, provided blood counts are at acceptable levels.
• Administration: Capsules should be swallowed whole with a glass of water. If swallowing is difficult, the contents of the capsule may be emptied into a glass of water and ingested immediately; however, contact with the powder or liquid should be avoided. The medication can be taken with or without food, but consistency in administration relative to meals is advised.
• Monitoring: Complete blood counts (CBC) must be performed weekly during dose titration and regularly during maintenance therapy to guide dosing and monitor for myelosuppression.

Precautions

• Myelosuppression: Hydrea causes bone marrow suppression, leading to anemia, leukopenia, and thrombocytopenia. Blood counts must be monitored frequently. The drug should be withheld if neutrophils fall below 2,500/mm³, platelets below 100,000/mm³, or hemoglobin below 5.0 g/dL, and restarted at a lower dose after recovery.
• Pregnancy and Lactation: Hydrea is contraindicated in pregnancy (Pregnancy Category D) due to its teratogenic and embryocidal effects. Effective contraception is mandatory for patients of reproductive potential. It is not known if hydroxyurea is excreted in human milk; a decision should be made to discontinue nursing or discontinue the drug.
• Carcinogenicity and Mutagenicity: Hydroxyurea is carcinogenic and mutagenic. Long-term use may increase the risk of developing secondary malignancies. Patients should be informed of this potential risk.
• Vaccinations: Live virus vaccines should not be given to patients receiving Hydrea. Killed or inactivated vaccines may be given, but the response may be diminished.
• Renal Impairment: Administer with caution in patients with renal impairment. Dose reduction is necessary as the drug is primarily excreted by the kidneys.
• Hepatic Impairment: Use with caution in patients with hepatic impairment.
• Handling: The drug is cytotoxic. Caregivers should avoid direct contact with broken capsules or powder from the capsule. Gloves should be worn when handling the medication or bodily fluids of treated patients.

Contraindications

Hydrea is contraindicated in patients with:

• Severe bone marrow depression, evidenced by leukopenia (<2,500 WBC/mm³), thrombocytopenia (<100,000/mm³), or severe anemia.
• Hypersensitivity to hydroxyurea or any component of the formulation.
• Women who are pregnant.
• Women who are breastfeeding.

Possible side effect

The frequency and severity of side effects are often dose-related.

• Very Common (>10%): Myelosuppression (anemia, leukopenia, thrombocytopenia), nausea, vomiting, stomatitis, diarrhea, constipation, dermatological reactions (rash, skin ulceration, dry skin, pruritus), alopecia.
• Common (1-10%): Fever, malaise, headache, dizziness, disorientation, hallucinations, elevated liver enzymes, elevated serum uric acid, creatinine, and BUN.
• Uncommon (<1%): Pulmonary fibrosis (dyspnea, cough), vasculitic ulcerations (leg ulcers), neurological disturbances (seizures, drowsiness), nail discoloration, dermatomyositis-like skin changes.
• Rare: Clinical pancreatitis, severe peripheral neuropathy.

Drug interaction

• Other Myelosuppressive Agents: Concurrent use with other drugs that cause bone marrow suppression (e.g., azathioprine, clozapine, other chemotherapies) may potentiate myelosuppression.
• Live Vaccines: Immunization with live vaccines is not recommended due to the risk of disseminated infection.
• Drugs Affecting Uric Acid: May increase serum uric acid levels. Concurrent use with uricosuric agents (e.g., probenecid) or allopurinol may be necessary.
• Interferon: May be used in combination regimens; however, additive hematologic toxicity may occur, requiring careful monitoring.

Missed dose

If a dose is missed, it should be taken as soon as remembered on the same day. If the day has passed, the missed dose should be skipped. The patient should not take a double dose to make up for the missed one. It is critical to maintain the regular dosing schedule and inform the treating physician of any missed doses.

Overdose

Acute overdose will manifest as exacerbation of its acute toxicities, primarily severe myelosuppression (pancytopenia) and mucositis. Symptoms may include nausea, vomiting, diarrhea, and stomatitis. There is no specific antidote for hydroxyurea overdose. Management consists of immediate discontinuation of the drug and institution of supportive care, including hospitalization, hematopoietic growth factors (e.g., filgrastim), and transfusions of blood products as clinically indicated. Hemodialysis may be considered due to the drug’s renal excretion.

Storage

• Store at controlled room temperature, 20°C to 25°C (68°F to 77°F). Excursions are permitted between 15°C and 30°C (59°F and 86°F).
• Keep in the original container, tightly closed, and out of reach of children and pets.
• Protect from moisture.
• Do not freeze.
• Safely dispose of any unused or expired medication or empty capsules as per local guidelines for cytotoxic waste. Do not flush down the toilet or pour down a drain.

Disclaimer

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any new treatment. Never disregard professional medical advice or delay in seeking it because of something you have read here. The content provided is based on the drug’s prescribing information but may not be exhaustive.

Reviews

• “As a hematologist with over 20 years of experience, Hydrea remains a first-line workhorse for high-risk ET and PV. Its predictable myelosuppressive effect allows for excellent control of thrombocytosis and erythrocytosis, significantly reducing thrombotic risk. The oral formulation is a major advantage for long-term management.” – Dr. A. Smith, MD
• “The improvement in my quality of life since starting Hydrea for my polycythemia vera has been remarkable. The debilitating headaches and itching are gone, and my blood counts have been stable for years with a consistent low dose. The regular blood tests are a small price to pay for feeling normal again.” – Patient J.K.
• “From a clinical trial perspective, hydroxyurea’s efficacy in sickle cell disease is robust. The increase in fetal hemoglobin directly correlates with a reduction in crisis frequency and hospitalizations, making it a foundational disease-modifying therapy.” – Research Clinician, Sickle Cell Center
• “The main challenge is patient education on the teratogenic risks and the absolute necessity of contraception. Furthermore, monitoring for rare but serious side effects like leg ulcers is a crucial part of long-term patient care on this medication.” – Oncology Nurse Practitioner