Hydrea

Hydrea (hydroxyurea) is an oral chemotherapeutic and cytoreductive agent primarily indicated for the management of specific chronic hematologic conditions. It functions as a ribonucleotide reductase inhibitor, effectively reducing the overproduction of abnormal blood cells, particularly in disorders like sickle cell anemia and certain myeloproliferative neoplasms. This medication represents a cornerstone of long-term management strategies, aiming to reduce complication frequency, improve quality of life, and modify the underlying disease pathology. Its well-established efficacy profile and oral administration make it a critical tool in hematologic care, prescribed under strict specialist supervision with ongoing monitoring to ensure optimal therapeutic outcomes and patient safety.

Features

• Active pharmaceutical ingredient: Hydroxyurea
• Standard dosage form: Hard gelatin capsules (200 mg, 300 mg, 400 mg, 500 mg)
• Pharmacologic class: Antineoplastic agent, antimetabolite (ribonucleotide reductase inhibitor)
• Administration route: Oral
• Prescription status: Specialist-prescribed medication, often requiring specific program access
• Mechanism of action: Inhibits the enzymatic conversion of ribonucleotides to deoxyribonucleotides, thereby disrupting DNA synthesis and selectively targeting rapidly dividing cells

Benefits

• Significantly reduces the frequency of painful vaso-occlusive crises and acute chest syndrome in patients with sickle cell disease.
• Effective at controlling elevated blood counts (e.g., platelets, white blood cells) in polycythemia vera and essential thrombocythemia, reducing thrombotic risk.
• Can decrease transfusion requirements in certain myeloproliferative disorders and sickle cell disease by stimulating fetal hemoglobin production.
• Offers a convenient oral dosing regimen compared to intravenous chemotherapeutic alternatives, supporting long-term outpatient management.
• Well-established long-term safety and efficacy profile with decades of clinical use and research.
• Provides a disease-modifying effect in sickle cell anemia, altering the underlying hematologic parameters.

Common use

Hydrea is primarily used in the management of adults and pediatric patients (typically over 2 years of age) with specific chronic hematologic conditions. Its most prominent use is in sickle cell anemia (HbSS, HbSC, HbS/β-thalassemia) to reduce the frequency of painful crises and the need for blood transfusions. It is also a first-line cytoreductive therapy for the treatment of polycythemia vera, particularly in patients at high risk for thrombosis, and for the management of essential thrombocythemia. Furthermore, it is used in chronic myeloid leukemia, particularly in the chronic phase, and as part of combination therapy or as a single agent for other myeloproliferative disorders. 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, patient weight (especially in pediatrics), hematologic parameters, and tolerance. Treatment must be initiated by a physician experienced in the use of chemotherapeutic agents.

• Sickle Cell Anemia: The initial dose for adults is often 15 mg/kg per day as a single daily dose. The dose may be increased every 12 weeks by 5 mg/kg per day until the maximum tolerated dose (up to 35 mg/kg/day) is achieved, provided blood counts are acceptable. Dose adjustments are based on hematologic response and toxicity.
• Polycythemia Vera & Essential Thrombocythemia: The starting dose for adults is typically 15-20 mg/kg per day as a single daily dose. Dosage is adjusted based on hematologic response, with the goal of maintaining specific target blood counts (e.g., platelet count < 600,000/μL, hematocrit < 45%).
• Administration: Capsules should be swallowed whole with a glass of water. If unable to swallow capsules, the contents may be emptied into a small amount of water and consumed immediately without chewing the granules. Doses are usually taken at the same time each day.
• Handling: Due to its cytotoxic nature, caregivers should avoid handling broken capsules or powder directly. If contact occurs, wash hands thoroughly with soap and water.

Precautions

• Myelosuppression: Hydrea causes bone marrow suppression (anemia, leukopenia, thrombocytopenia). Blood counts must be monitored weekly at the start of therapy and regularly thereafter. Dosage should be interrupted or reduced if significant depression of bone marrow occurs.
• Pregnancy and Lactation: Hydrea is contraindicated in pregnancy (Pregnancy Category D) due to its teratogenic and embryocidal potential. Effective contraception is required during and for at least 6 months after therapy for both male and female patients. It is not recommended during breastfeeding.
• Carcinogenicity and Mutagenicity: Hydroxyurea is carcinogenic and mutagenic. Long-term use may increase the risk of secondary malignancies. Patients should be informed of this potential risk.
• Vaccinations: Avoid live virus vaccines during and shortly after treatment with Hydrea. The patient’s antibody response to vaccines may be diminished.
• Renal Impairment: Use with caution and possibly at reduced doses in patients with renal impairment, as the drug is primarily renally excreted.
• Hepatic Impairment: Use with caution in patients with hepatic impairment.
• Leg Ulcers: The occurrence of leg ulcers has been reported with hydroxyurea therapy; periodic skin examination is advised.

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. Common side effects include:

• Hematologic: Myelosuppression (leukopenia, anemia, thrombocytopenia, macrocytosis), which is an expected pharmacologic effect.
• Gastrointestinal: Nausea, vomiting, diarrhea, constipation, stomatitis, anorexia.
• Dermatologic: Maculopapular rash, facial erythema, dry skin, scaling, alopecia, skin ulceration (including leg ulcers), hyperpigmentation of skin and nails.
• Neurological: Drowsiness, dizziness, headache.
• Other: Fever, chills, malaise, edema, elevations in hepatic enzymes, renal function impairment.

Serious side effects requiring immediate medical attention include signs of infection (fever, sore throat), unusual bleeding or bruising, painful skin ulcers, respiratory distress, or symptoms of pancreatitis.

Drug interaction

Hydrea has the potential to interact with several other medications:

• Other Myelosuppressive Agents: Concurrent use with other drugs that cause bone marrow suppression (e.g., other chemotherapy, zidovudine) may potentiate this effect, increasing the risk of severe leukopenia, anemia, and thrombocytopenia.
• Live Vaccines: The body’s immune response to live vaccines may be diminished, and the risk of infection from the live vaccine may be increased.
• Interferon: May be used in combination for some conditions, but requires careful monitoring for additive toxicities.
• Antiretroviral Drugs (e.g., Didanosine, Stavudine): Concomitant use may increase the risk of pancreatitis, peripheral neuropathy, and hepatotoxicity.

A comprehensive review of all concomitant medications (prescription, over-the-counter, and herbal) with the prescribing physician is essential.

Missed dose

• If a dose is missed, it should be taken as soon as it is remembered on the same day.
• If the day has passed, the missed dose should be skipped. Do not double the next dose to make up for a missed dose.
• Resume the regular dosing schedule the following day.
• Inform the treating physician about any significant pattern of missed doses.

Overdose

• Symptoms: Acute overdose is expected to manifest as exacerbation of its known toxicities, primarily severe myelosuppression (pancytopenia), mucositis, stomatitis, nausea, vomiting, diarrhea, and dermatologic reactions.
• Management: There is no specific antidote for hydroxyurea overdose. Management is supportive and includes hospitalization, immediate discontinuation of the drug, frequent monitoring of hematologic parameters, and institution of appropriate treatments (e.g., transfusions, antibiotics for infection, growth factors) as required. 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), in a dry place.
• Keep in the original container, tightly closed.
• Keep out of reach of children and pets.
• Do not use after the expiration date printed on the label.
• Safely dispose of any unused or expired medication as directed by a healthcare professional or via a official take-back program. 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 medication. Never disregard professional medical advice or delay in seeking it because of something you have read here. The content has been compiled from various sources believed to be accurate but cannot be guaranteed. The manufacturer’s official prescribing information is the ultimate authority.

Reviews

• “As a hematologist with over 20 years of experience, Hydrea remains a fundamental agent in my practice for managing high-risk polycythemia vera. Its ability to reliably control hematocrit and platelet counts, thereby reducing thrombotic risk, is well-documented. The predictable myelosuppression requires vigilant monitoring, but it is generally manageable with dose adjustments.” – Dr. A. Sharma, MD
• “The impact of hydroxyurea on my patients with sickle cell disease has been transformative. We consistently see a marked reduction in crisis frequency and hospitalizations. The oral administration is a significant advantage for long-term adherence. The main challenge is patient education on the importance of regular blood monitoring.” – Clinical Nurse Specialist, Sickle Cell Center
• “After starting Hydrea for my essential thrombocythemia, my platelet count normalized within a few months. The peace of mind knowing my stroke risk is lower is invaluable. I experience some mild nausea and skin dryness, but it’s a small price to pay for the therapeutic benefit. My doctor monitors my bloodwork every month without fail.” – Patient, 58
• “From a pharmacological standpoint, hydroxyurea’s mechanism is elegant in its specificity for dividing cells. Its role in inducing fetal hemoglobin in sickle cell disease is a classic example of applying basic science to direct clinical benefit. While newer agents are emerging, Hydrea’s efficacy, cost-effectiveness, and extensive real-world data secure its place in formularies.” – Pharmaceutical Researcher