CYTODROX is used to treat certain types of cancer (melanoma, chronic myelocytic leukemia, cancer of the ovary, and primary skin cancer of the head and neck) or sickled red blood cells. Active ingredient of this drug is hydroxyurea. The exact mechanism of its action is unknown, it is supposed that it is cell cycle specific for the S phase of cell division, it interfere with synthesis of DNA, with no effect on synthesis of RNA or protein