Hydroxycarbamid Hikma (Hydroxycarbamide)

Hydroxycarbamide is used to treat hematologic disorders that involve abnormal cell proliferation.

• Sickle cell disease: reduces the frequency of painful vaso‑occlusive crises, improves anemia, and decreases the need for blood transfusions.
• Chronic myelogenous leukemia: decreases leukemic cell proliferation, contributes to cytogenetic remission, and supports long‑term disease control when combined with targeted therapy.
• Polycythemia vera: lowers elevated red blood cell mass, helps control hematocrit levels, and reduces the risk of thrombotic complications.
• Essential thrombocythemia: helps control excessive platelet production and lowers the risk of clotting events.

• Hydroxycarbamide inhibits the enzyme ribonucleotide reductase, which is essential for the conversion of ribonucleotides to deoxyribonucleotides. By limiting the supply of deoxyribonucleotides, DNA synthesis is impaired, leading to reduced replication of rapidly dividing cells such as malignant hematopoietic cells and abnormal erythroid precursors. The drug’s effect is dose‑dependent and reversible upon discontinuation.

Hydroxycarbamide may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset, often manageable with food or anti‑emetics.
• Fatigue: persistent tiredness that may limit daily activities and require dose adjustment.
• Hair thinning: temporary loss of scalp hair, usually reversible after stopping therapy.
• Skin hyperpigmentation: gradual darkening of skin, especially on the face, hands, or nails.

Serious or Rare Side Effects

• Myelosuppression: marked decrease in white cells, platelets, or red cells, raising infection, bleeding, and anemia risk.
• Renal toxicity: impaired kidney function indicated by rising creatinine or reduced glomerular filtration rate.
• Severe cutaneous reactions: life‑threatening skin conditions such as Stevens‑Johnson syndrome or toxic epidermal necrolysis.

When prescribing hydroxycarbamide, clinicians should observe several precautions to minimise risks and ensure safe use.

• Baseline monitoring: obtain complete blood count and renal function tests before initiating therapy.
• Dose adjustments: modify dose in patients with pre‑existing cytopenias or renal impairment.
• Pregnancy considerations: avoid use unless benefits outweigh potential fetal risks; discuss with obstetric specialist.
• Concomitant medications: review drugs that may exacerbate myelosuppression or renal toxicity.
• Store at ambient temperature: keep tablets in original container, protect from moisture and direct sunlight.

Hydroxycarbamide can interact with several medicines, altering its efficacy or toxicity.

Major Interactions (Avoid)

• Antiretroviral agents (e.g., zidovudine): combined use may increase bone‑marrow suppression, leading to severe cytopenias.
• Cytarabine or other nucleoside analogues: additive myelosuppressive effect can result in profound neutropenia and thrombocytopenia.

Moderate Interactions (Monitor Closely)

• Allopurinol: may increase hydroxycarbamide plasma levels, requiring careful dose review and monitoring of blood counts.
• NSAIDs: can worsen renal function when used together, especially in patients with pre‑existing kidney disease.
• Live vaccines: immunosuppression may reduce vaccine efficacy and increase risk of infection.
• Phenytoin: may reduce hydroxycarbamide effectiveness through enzyme induction, potentially necessitating dose adjustment.
• Azathioprine: combined therapy can intensify bone‑marrow suppression, demanding close hematologic surveillance.
• Methotrexate: overlapping toxicity may increase risk of cytopenias and hepatic strain.