Chronic Myeloid Leukemia (CML):
- Adults: 20–30 mg/kg/day orally
- Adjust according to white blood cell (WBC) response
Sickle Cell Anemia (SCA):
- Adults & children >2 years: Initial dose 15 mg/kg/day (10 mg/kg/day in renal impairment)
- Increase by 5 mg/kg every 12 weeks up to maximum 35 mg/kg/day
- Monitor blood counts regularly
Polycythemia Vera & Essential Thrombocythemia:
- Starting dose: ~15–20 mg/kg/day
- Adjust based on hematologic response
Head & Neck Cancer (in combination with radiation):
- 80 mg/kg every 3 days orally
- Begin 7 days before radiotherapy
- Capsules: 200 mg, 300 mg, 400 mg, 500 mg
- Tablets (e.g., Siklos): 100 mg, 1,000 mg (scored for pediatric dosing)
- Take with or without food, preferably at the same time daily.
- Swallow whole; do not crush or open capsules (cytotoxic).
- Adequate hydration is important to reduce GI irritation and prevent uric acid build-up.
Mechanism of Action:
- Inhibits ribonucleotide reductase, blocking DNA synthesis in the S-phase of the cell cycle.
- In sickle cell disease, increases fetal hemoglobin (HbF) levels, reducing sickling and vaso-occlusive crises.
Pharmacokinetics:
- Absorption: Rapid, nearly complete
- Half-life: ~3–4 hours
- Metabolism: Liver (partial)
- Excretion: Primarily renal
- Bone marrow suppression (neutropenia, thrombocytopenia, anemia)
- Gastrointestinal: nausea, vomiting, diarrhea, constipation
- Mucositis
- Fever
- Skin ulcerations
- Hyperpigmentation or rash
- Elevated liver enzymes, creatinine, or BUN
- Hypersensitivity to hydroxyurea
- Severe bone marrow depression
- Pregnancy (especially 1st trimester)
- Breastfeeding
- Antiretroviral agents (especially didanosine, stavudine): Increased risk of pancreatitis, hepatotoxicity, and neuropathy
- Myelosuppressive agents: Additive effects on bone marrow suppression
- Live vaccines: Avoid due to immunosuppressive effects
Drug Status
Availability | |
Pregnancy | |
Breastfeeding | |
Schedule |
BRAND NAME | STRENGTH | FORMULATION | PACK SIZE | MANUFACTURER | DISTRIBUTOR |
---|---|---|---|---|---|
Riborea | 500mg | Capsule | 100’s | PSM Pharma | PSM Pharma |