The second mechanism is by directly enhance the fetal hemoglobin production due to that during the metabolism of hydroxyurea there is a huge amount of nitric oxide where produced and lead to the stimulation of heme iron containing enzyme, soluble guanylate cyclase, and as a result of this reaction a fetal hemoglobin will produced (Platt, 2008). Therefore, hydroxyurea overcome the bad effects of sickle hemoglobin (HbS), which causes a damage of the cell membrane by different ways leads to hemolysis and the loss of endogenous nitric oxide, on red blood cells (Platt, 2008). Hydroxyurea had excellent oral bioavailability and a half-life ranging from 2-4 hours which means a relatively rapid clearance in both adult and children (Ware et al., 2002). Also, it found to increase fetal hemoglobin (HbF) concentration from 10% to 40% when administered at maximum tolerated dose (MTD) (Ware et al., 2002; Iolascon et al.,
The second mechanism is by directly enhance the fetal hemoglobin production due to that during the metabolism of hydroxyurea there is a huge amount of nitric oxide where produced and lead to the stimulation of heme iron containing enzyme, soluble guanylate cyclase, and as a result of this reaction a fetal hemoglobin will produced (Platt, 2008). Therefore, hydroxyurea overcome the bad effects of sickle hemoglobin (HbS), which causes a damage of the cell membrane by different ways leads to hemolysis and the loss of endogenous nitric oxide, on red blood cells (Platt, 2008). Hydroxyurea had excellent oral bioavailability and a half-life ranging from 2-4 hours which means a relatively rapid clearance in both adult and children (Ware et al., 2002). Also, it found to increase fetal hemoglobin (HbF) concentration from 10% to 40% when administered at maximum tolerated dose (MTD) (Ware et al., 2002; Iolascon et al.,