Role of hydroxycarbamide in prevention of complications in patients with sickle cell disease.

Sickle cell disease (SCD) is a genetically inherited condition caused by a point mutation in the beta globin gene. This results in the production of the abnormal hemoglobin, sickle hemoglobin (HbS). Hydroxycarbamide, is an antimetabolite/cytotoxic which works by inhibiting ribonucleotide reductase, blocking the synthesis of DNA and arresting cells in the S phase. In sickle cell anemia, it promotes fetal hemoglobin (HbF) synthesis, improves red cell hydration, decreases neutrophil and platelet count, modifies red cell endothelial cell interactions and acts as a nitric oxide donor. Trials have shown the clinical benefit of hydroxycarbamide in a subpopulation of adult patients with SCD, with a 44% reduction in the median annual rate of painful crises, a decrease in the incidence of acute chest syndrome and an estimated 40% reduction in overall mortality over a 9-year observational period. Its use in pediatrics has also been well established; trials have shown it is well tolerated and does not impair growth or development. In addition it decreases the number and duration of hospital attendences. A number of emerging uses of hydroxycarbamide currently are being investigated, such as stroke prevention.