<s>[INST] context: Hydroxyurea: It blocks the conversion of ribonucleotides to deoxyribonucleotides by inhibiting the enzyme ribonucleoside diphosphate reductase-thus interferes with DNA synthesis; exes S-phase specific action. Its primary therapeutic value is in chronic myeloid leukaemia, psoriasis, polycythaemia vera and in some solid tumours. Myelosuppression is the major toxicity. Hydroxyurea (Droxia) is used to reduce the frequency of painful crises and reduce the need for blood transfusions in patients with sickle cell anemia (an inherited blood disorder in which the red blood cells are abnormally shaped and cannot bring enough oxygen to all pas of the body). Hydroxyurea is in a class of medications called antimetabolites. Hydroxyurea treats cancer by slowing or stopping the growth of cancer cells in your body. Hydroxyurea treats sickle cell anemia by helping to prevent formation of sickle-shaped red blood cells ESSENTIALS OF MEDICAL PHARMACOLOGY, www.medlineplus.gov K.D.TRIPATHI SIXTH EDITION PAGE NO:827 [/INST] question: Which of the following drug is used for the treatment of sickle cell anemia? | options: A: Hydroxyurea B: Cisplatin C: Paclitaxel D: Carboplatin | answer: A </s>