Final answer:
Hydroxyurea is the most commonly used drug in the treatment of polycythemia vera, a disease characterized by an excessive production of red blood cells.
Step-by-step explanation:
The drug most commonly used in the treatment of polycythemia vera is hydroxyurea. Polycythemia vera is a type of bone marrow disease that leads to an excessive production of immature erythrocytes raising the blood's viscosity and causing complications such as high blood pressure and increased workload on the heart. Hydroxyurea works by reducing the production of red blood cells, which helps to decrease the blood's viscosity and improve symptoms.
Although erythropoietin (EPO) indirectly relates to the condition by stimulating RBC production, it is not used to treat polycythemia vera. Instead, synthetic EPO is known for its misuse as a performance-enhancing drug in sports through blood doping, which may induce polycythemia. The management of polycythemia vera may involve other treatments as well, including phlebotomy, low-dose aspirin and other cytoreductive agents depending on the patient's symptoms and risk factors.