Hydrea (Hydroxycarbamide)

Hydrea is indicated for several hematologic conditions where abnormal cell proliferation is a concern.

• Chronic myelogenous leukemia (CML) as part of disease‑modifying therapy.
• Polycythemia vera to reduce elevated red blood cell mass.
• Essential thrombocythemia for controlling platelet overproduction.
• Sickle cell disease to decrease frequency of vaso‑occlusive crises.
• Occasionally used off‑label for other myeloproliferative neoplasms under specialist supervision.

• Hydroxycarbamide inhibits the enzyme ribonucleotide reductase, which is essential for converting ribonucleotides to deoxyribonucleotides. By limiting the supply of deoxyribonucleotides, the drug reduces DNA synthesis during the S‑phase of the cell cycle, leading to decreased proliferation of rapidly dividing cells, including malignant leukemic cells and abnormal erythroid precursors. This antimetabolite effect underlies its therapeutic activity in myeloproliferative disorders and sickle cell disease.

Hydroxycarbamide may cause a range of adverse reactions, which are generally categorized by frequency and severity.

Common

• Mild nausea, vomiting, or loss of appetite.
• Transient low white‑blood‑cell counts (neutropenia) that resolve with monitoring.
• Skin discoloration or hyperpigmentation, especially on the face and hands.
• Hair thinning or temporary alopecia.

Serious

• Severe bone‑marrow suppression leading to pancytopenia.
• Acute renal impairment or elevated serum creatinine.
• Life‑threatening hypersensitivity reactions, including Stevens‑Johnson syndrome.

Before initiating Hydrea, clinicians consider several safety precautions to minimize risk.

• Pregnancy category D; use only when potential benefit outweighs fetal risk.
• Avoid in patients with pre‑existing severe renal or hepatic impairment.
• Baseline and regular complete blood counts are required to monitor for marrow toxicity.
• Counsel patients on the risk of leg ulcers and skin changes.
• Discontinue or adjust dose if significant cytopenias develop.
• Use caution in individuals with a history of gout, as uric acid levels may rise.

Hydroxycarbamide can interact with other medications, affecting its efficacy or safety profile.

Avoid

• Concurrent use of other myelosuppressive agents (e.g., azathioprine, cyclophosphamide) that may exacerbate bone‑marrow suppression.
• Live vaccines, because immunosuppression can increase infection risk.

Use with caution

• Antiretroviral drugs such as zidovudine, which may enhance hematologic toxicity.
• NSAIDs or aspirin, which can increase the risk of gastrointestinal bleeding when platelet counts are low.
• Allopurinol or other uric‑acid‑lowering agents, requiring monitoring for gout flares.