Which of the following drugs is used in sickle cell anaemia?

Ans. is 'b' i.e., Hydroxyurea Hydroxyurea* It blocks the conversion of ribonucleotides to the deoxyribonucleotides by inhibiting the enzyme ribonucleoside diphosphate reductase, which interferes with DNA synthesis.* It exerts S phase specific action.* Myelosuppression is a major toxicity* The most significant advance in the therapy of sickle cell anemia has been the introduction of hydroxyurea as a mainstay of therapy for patients with severe symptoms.* Hydroxyurea (10-30 mg/kg per day) increases fetal hemoglobin and may also exert beneficial affects on RBC hydration, vascular wall adherence, and suppression of the granulocyte and reticulocyte counts; dosage is titrated to maintain a white cell count between 5000 and 8000 per mL.* White cells and reticulocytes may play a major role in the pathogenesis of sickle cell crisis, and their suppression may be an important benefit of hydroxyurea therapy.* Hydroxyurea should be considered in patients experiencing repeated episodes of acute chest syndrome or with more than three crises per year requiring hospitalization. The utility of this agent for reducing the incidence of other complications (priapism, retinopathy) is under evaluation, as are the long-term side effects.* Hydroxyurea offers broad benefits to most patients whose disease is severe enough to impair their functional status, and it may improve survival. HbF levels increase in most patients within a few months.