All children older than nine months with proven SCD; and in adolescents and adults with the following;
- Recurrent vaso-occlussive crisis (3 or more severe episodes requiring admission in the last 12 months),
- Severe and/or recurrent acute chest syndrome (ACS) (2 or more episodes in a lifetime),
- Severe symptomatic chronic anemia that interferes with daily activities or quality of life,
- Where chronic transfusion therapy is not feasible use it as an alternative to prevent new or recurrent stroke,
- Silent infarcts, stroke and in patients with abnormal TCD (199cm/sec),
- Recurrent priapism,
- Chronic kidney disease on erythropoietin to improve anaemia.
Principle of Dosage Initiation and Monitoring:
S: hydroxyurea (PO) 15 mg/kg/day 24hourly; (5–10 mg/kg/day if patient has chronic kidney disease).
S: hydroxyurea (PO) 20mg/kg/day, starting dosage for infants and children.
Increase the dose by 2.5–5 mg/kg/day every 3 months,Maximum tolerated dose (MTD) should not exceed 30mg/kg/day.
Blood work monitoring
- Bi-monthly FBP, reticulocyte count for 1 month, then monthly for 3months, then once every 3months if blood counts remain stable.
- HbF % analysis, liver function test, serum creatinine and urea every 6months.
- Weigh patient every three months and adjust the dosage accordingly.
Threshold for dose reduction
- Neutrophil ANC < 1.5 X109/L
- Reticulocyte count < 80 X1012/L
- Platelet count < 80 X109/L
- Hb < 6g/dl
If haematologic toxicity occurs;
- Discontinue hydroxyurea until counts recover, usually 1-2 weeks,
- Reinitiate hydroxyurea at a dose 2.5 mg/kg/day less than the dose given before onset of cytopenias to achieve the maximum tolerable therapeautic dose,
- Do FBP according to the initiation schedule.
Note:
- Clinical response to treatment with hydroxyurea may take 3-6months. A 6month trial on MTD is required before considering discontinuation due to treatment failure.
- Hydroxyurea should be stopped at least three months prior to conception in both males and females
- Hydroxyurea should be discontinued in all pregnant women
- Hydroxyurea should be discontinued in all breastfeeding women