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Hydroxyurea (Hydroxycarbamide)
💊 About
- Hydroxycarbamide (Hydroxyurea) is an antimetabolite cytotoxic drug.
- Always check the BNF entry here for current dosing and cautions.
⚙️ Mode of Action
- Inhibits ribonucleotide reductase → blocks conversion of ribonucleotides to deoxyribonucleotides.
- Disrupts DNA synthesis by impairing purine and pyrimidine production.
- Acts in the S phase of the cell cycle.
🎯 Indications / Dosing (specialist-led)
- Chronic Myeloid Leukaemia (CML): Start at ~40 mg/kg daily, adjust to white cell count.
- Myeloproliferative disease: Polycythaemia vera (PV), Essential thrombocythaemia (ET), Myelofibrosis (MF).
- Psoriasis (refractory cases): 500–1500 mg/day in divided doses, under dermatology supervision.
- Sickle Cell Disease:
- Initial 15 mg/kg daily PO.
- Increase every 12 weeks by 2.5–5 mg/kg depending on response.
- Usual dose 15–30 mg/kg/day (max 35 mg/kg).
- Mechanism here: ↑ fetal Hb (HbF), ↓ sickling crises.
🤝 Interactions
- See BNF for details.
- Other myelosuppressants or radiotherapy → ↑ toxicity risk.
⚠️ Cautions
- 📈 FBC monitoring essential: Baseline → every 2 weeks for first 2 months → then every 2 months (or 2-weekly if on max dose).
- Infection risk: Patients must seek urgent advice if temperature ≥37.5–38°C or if unwell (sore throat, cough, diarrhoea, urinary frequency, unexplained bruising).
- Renal impairment: dose adjustments required.
- Carcinogenic potential (long-term use).
🚫 Contraindications
- Pregnancy and breastfeeding (teratogenic risk).
- Severe bone marrow suppression or marked anaemia.
- Refer to BNF for full list.
❗ Side Effects
- Bone marrow suppression (onset 7–21 days).
- Mild GI: Nausea, vomiting, diarrhoea.
- Mucositis and mouth ulcers.
- Skin and nail pigmentation, leg ulcers (with long-term use).
- Biochemical: ↑ creatinine, ↓ magnesium.
📚 References
| The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms. |
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