Hydrea (Hydroxycarbamide)

Hydrea (hydroxycarbamide) is indicated for several hematologic malignancies and blood disorders, as well as for specific solid tumor indications, under the direction of a qualified health professional.

• Chronic myelogenous leukemia (CML), especially in patients who have failed or are intolerant to tyrosine‑kinase inhibitors
• Polycythemia vera (PV) to control elevated red blood cell mass
• Essential thrombocythemia (ET) for reduction of platelet counts and thrombotic risk
• Sickle cell disease (SCD) to decrease frequency of vaso‑occlusive crises
• Melanoma, often as part of combination chemotherapy regimens

• Hydroxycarbamide inhibits the enzyme ribonucleotide reductase, which is essential for the conversion of ribonucleotides to deoxyribonucleotides. By reducing the intracellular pool of deoxyribonucleotides, the drug impairs DNA synthesis and repair, leading to cell cycle arrest primarily in the S‑phase. This antimetabolite effect preferentially affects rapidly proliferating malignant and hematopoietic cells, contributing to its therapeutic activity in leukemias, myeloproliferative disorders, and certain solid tumors.

Hydroxycarbamide may cause a range of adverse reactions, varying from mild to potentially life‑threatening. These effects can be dose‑related and may require monitoring of laboratory parameters during therapy.

Common

• Nausea or vomiting
• Mild skin rash or pruritus
• Transient elevation of liver enzymes (ALT/AST)
• Decreased blood counts (neutropenia, thrombocytopenia)
• Mouth ulcers or stomatitis

Serious

• Severe bone marrow suppression leading to pancytopenia
• Acute hemolytic crisis in patients with G6PD deficiency
• Pulmonary toxicity, including interstitial pneumonitis
• Renal impairment or failure
• Severe cutaneous reactions such as Stevens‑Johnson syndrome

When prescribing or taking Hydrea, several precautions should be observed to minimize risks and ensure safe use.

• Pregnancy is contraindicated (Category D); avoid use unless benefits outweigh risks
• Perform baseline and periodic complete blood counts to monitor for myelosuppression
• Assess liver and renal function before initiation and during treatment
• Screen for glucose‑6‑phosphate dehydrogenase deficiency to prevent hemolysis
• Counsel patients on the importance of contraception and avoiding pregnancy
• Monitor for signs of infection, fever, or bleeding
• Adjust dose in patients with significant hepatic or renal impairment

Hydroxycarbamide can interact with other medicines, affecting its efficacy or increasing toxicity.

Avoid

• Concurrent use with other myelosuppressive agents (e.g., cytarabine, azacitidine) due to additive bone‑marrow suppression
• Combining with live vaccines, as immunosuppression may reduce vaccine effectiveness

Use with caution

• Antiretroviral drugs such as zidovudine, which may enhance hematologic toxicity
• NSAIDs or aspirin, which can increase risk of gastrointestinal bleeding
• Drugs that affect renal excretion (e.g., probenecid) may alter hydroxycarbamide levels
• Vitamin C supplements, which may increase hydroxycarbamide absorption