This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Neoplastic Agents, Subject name: Pharmacology
Which of the following drug is used in sickle cell anemia? 
Select and explain. 
A. Hydroxyurea, B. Carmustine, C. Paclitaxel, D. Bleomycin
A: Hydroxyurea
Answer: A: Hydroxyurea 
Explanation: Ans. a. Hydroxyurea The only drug approved by US FDA for the treatment of sickle cell anemia is hydroxyurea.Hydroxyurea in Sickle Cell Anemia* The only drug approved by US FDA for the treatment of sickle cell anemia is hydroxyurea.* Hydroxyurea increases total and fetal hemoglobin in children with sickle cell disease.* The increase in fetal hemoglobin retards sickling of RBCs.* Hydroxyurea also reduces the level of circulating leucocytes. This decreases the adherence of neutrophils to the vascular endothelium in turn theses effects reduce the incidence of pain episodes and acute chest syndrome episodes.