Cytotoxic / Disease-Modifying Agent Pregnancy: D

Hydroxycarbamide (Hydroxyurea)

Brand names: Xagrid, Siklos, Hydrea

Adult dose

Dose: Sickle cell: 15 mg/kg/day, titrate up by 5 mg/kg every 12 weeks to max 35 mg/kg/day; ET: 500–1000 mg/day

Route: oral

Frequency: once daily

Max: 35 mg/kg/day

Siklos formulation licensed specifically for sickle cell; increases HbF production; wear gloves when handling if carer

Dose: 15 mg/kg

Route: oral

Frequency: once daily

Max: 35 mg/kg/day

Concentration: Siklos 100 mg/mL or 100 mg tablets mg/ml

Sickle cell disease: start 15 mg/kg/day; increase every 8–12 weeks; monitor every 4 weeks; avoid if ANC <2×10⁹/L or Plt <80×10⁹/L

Renal

Reduce dose if eGFR <60 ml/min; avoid if eGFR <10 ml/min

Hepatic

Use with caution

Paediatric weight-based calculator

Patient weight (kg)

Sickle cell disease: start 15 mg/kg/day; increase every 8–12 weeks; monitor every 4 weeks; avoid if ANC <2×10⁹/L or Plt <80×10⁹/L

Increases HbF — reduces sickling, crisis frequency, and mortality in sickle cell disease (MSH trial: 44% reduction in pain crises)
Leg ulcers: reversible on dose reduction — monitor lower limbs
Teratogen: double contraception in both male and female patients

Reference: BNFc; BNF 86; NICE NG143; MSH trial. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways