Hydroxyurea Medac (Hydroxycarbamide)

Hydroxyurea Medac, an antimetabolite that inhibits ribonucleotide reductase, is used in several hematologic and oncologic conditions.

• Sickle cell disease: decreases vaso‑occlusive episodes and raises fetal hemoglobin levels, helping to reduce anemia complications.
• Chronic myelogenous leukemia: slows proliferation of malignant myeloid cells, contributing to disease control.
• Polycythemia vera: lowers elevated red blood cell mass, helping to manage hematocrit and reduce thrombotic risk.
• Melanoma: used as part of combination therapy to inhibit tumor cell growth.

• Hydroxyurea (hydroxycarbamide) acts by irreversibly inhibiting the enzyme ribonucleotide reductase, which is essential for conversion of ribonucleotides to deoxyribonucleotides. This blockade reduces the intracellular pool of deoxyribonucleic acid precursors, thereby suppressing DNA synthesis and limiting cell division, particularly in rapidly proliferating hematopoietic and malignant cells. The resulting decrease in DNA replication triggers cell‑cycle arrest in the S phase and can induce fetal hemoglobin production in erythroid precursors, contributing to its therapeutic effects in sickle cell disease.

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

Common Side Effects

• Bone marrow suppression: anemia, neutropenia, thrombocytopenia, which may cause fatigue, increased infection risk and bleeding tendencies.
• Gastrointestinal upset: nausea, vomiting, abdominal pain or discomfort, often transient.
• Skin changes: hyperpigmentation of the skin or mild rash, usually reversible after discontinuation.
• Elevated liver enzymes: mild increases in transaminases (ALT, AST) without clinical hepatitis.
• Fatigue: persistent tiredness affecting daily activities.
• Hair loss: mild alopecia that may be temporary.

Serious or Rare Side Effects

• Severe myelosuppression: life‑threatening pancytopenia requiring transfusion support.
• Acute renal failure: sudden loss of kidney function, manifested by elevated creatinine.
• Severe cutaneous reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis, presenting with extensive skin detachment.
• Teratogenic effects: potential fetal malformations if exposure occurs during pregnancy.
• Hypersensitivity reactions: fever, chills, hypotension or anaphylaxis.

Precautions for Hydroxyurea Medac focus on monitoring blood parameters, organ function and patient counseling.

• Baseline assessment: obtain complete blood count and renal/hepatic function tests before initiating therapy.
• Monitoring: perform regular CBC, liver enzymes and kidney function during treatment to detect myelosuppression or toxicity.
• Infection risk: advise patients to report signs of infection promptly and to avoid exposure to contagious diseases.
• Pregnancy considerations: avoid use in pregnant women unless benefits outweigh risks; discuss contraception.
• Drug interactions: review concomitant medications for potential additive myelosuppressive effects.
• Store at ambient temperature: keep below 25°C in the original packaging, protect from moisture and direct sunlight.

Hydroxyurea can interact with several medicines, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Concurrent use with other myelosuppressive agents (e.g., cytarabine, azathioprine) may cause profound bone marrow depression.
• Strong CYP2D6 inhibitors (e.g., fluoxetine, paroxetine) can increase hydroxyurea plasma levels, raising toxicity risk.

Moderate Interactions (Monitor Closely)

• Allopurinol may enhance hydroxyurea toxicity; monitor blood counts.
• NSAIDs can affect renal function when combined with hydroxyurea; assess renal parameters.
• Antiretroviral protease inhibitors may alter hydroxyurea metabolism; adjust dosing if needed.
• Trimethoprim‑sulfamethoxazole may potentiate myelosuppression; regular CBC monitoring is advised.
• High-dose vitamin C may reduce hydroxyurea efficacy; patients should limit excessive supplementation.