A drug used to treat anemia caused by chronic kidney disease and some types of chemotherapy. Darbepoetin alfa is a form of erythropoietin (a substance naturally made by the kidneys) that is made in the laboratory. It helps the bone marrow make more red blood cells. Darbepoetin alfa is a type of antianemic and a type of erythropoiesis-stimulating agent. Also called Aranesp.