A drug used to treat neutropenia (a condition in which there is a lower-than-normal number of white blood cells) caused by some types of chemotherapy. It is used to help prevent infection in patients with certain types of cancer. Filgrastim-SD/01 is also used to help prevent damage to the bone marrow in patients who were exposed to high doses of certain types of radiation. Filgrastim-SD/01 helps the bone marrow make more white blood cells. It is a form of filgrastim and is able to stay in the body longer. Filgrastim-SD/01 is a type of colony-stimulating factor. Also called Neulasta and pegfilgrastim.