Riborea 500mg Capsule 10’s belongs to a group of classes known as an antimetabolite. It is an anticancer medicine used to treat head and neck cancer and sickle cell anemia (blocking the flow of blood that causes pain and organ damage). Head and neck cancer is a disease including abnormal growth of the tissues of the neck and head that may also have the ability to attack or spread to other portions of the body. Sickle cell anemia is a disease in which your body results in abnormally shaped red blood cells. The cells are shaped like a curved or sickle.