Neupogen® (Filgrastim): General Information for Clinicians

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What is Neupogen® (Filgrastim)?

Neupogen® (Filgrastim), is a drug that has been used successfully for cancer patients to produce more white blood cells (granulocytes or neutrophils). Neupogen® is indicated to decrease the incidence of infection resulting from neutropenia (low white blood cells counts) in cancer patients receiving treatment. Neupogen® is also expected to help patients who have bone marrow damage from very high doses of radiation in much the same way.

A person who has received a very high dose of penetrating ionizing radiation (greater or equal to 2 Gray [Gy] to the whole body over a short duration) may experience bone marrow damage, possibly resulting in infection (triggered by neutropenia) and uncontrolled bleeding.

In March 2015, Neupogen® was also approved by the U.S. Food and Drug Administration (FDA) to treat those people who have received high doses of radiation. For more information refer to the Neupogen® package insert.

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How does Neupogen® work?

Patients who have been exposed to high doses of radiation will not be able to produce new white blood cells, leading to a significant decrease in the number of white blood cells (including neutrophils) in circulation:

  • These patients’ own bone marrow will eventually create new blood cells, but this process is slow.
  • Until their white blood cell counts rise sufficiently, these patients are at a high risk of death from infection because of severe neutropenia.

Neupogen® can accelerate the process of creating white blood cells, reducing the time that the patient is vulnerable to infection.

For additional information, review the Information Sheet on Acute Radiation Syndrome.

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Can Neupogen® remove radioactive material from the body?

No. Neupogen® is given to help cancer and/or patients exposed to high doses of radiation produce white blood cells at a faster pace to avoid or minimize the incidence of infections resulting from neutropenia. However, Neupogen® cannot help the patient in eliminating or blocking the absorption of radioisotopes or any radioactive material from inside the body.

To learn about medical countermeasures available for internal radiation contamination by specific radioactive material, refer to the following links:

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Who can take Neupogen®?

Neupogen® can be used in adults and children of all ages, including pregnant and nursing women for whom Neupogen® is deemed clinically appropriate. Neupogen® should not be taken by people who have known hypersensitivity to filgrastim, peg-filgrastim, or any component of filgrastim such as E. coli-derived proteins.

Pregnant Women (Category C)

There is a lack of adequate and well-controlled studies in pregnant women. Some adverse effects have been observed in animal studies. Neupogen® should be used during pregnancy only if the potential benefit outweighs the potential risk to the fetus.

Nursing mothers

It is not known whether Neupogen® is excreted in human milk. Because many drugs are excreted in human milk‚ caution should be exercised if Neupogen® is administered to women who are breastfeeding.

Note: Neupogen® is available in single-dose vials and prefilled syringes. The needle cap on the prefilled syringes contain dry natural rubber, derived from latex. In persons with known severe latex allergies, precautions should be taken when handling and/or administering Neupogen® from prefilled syringes.

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How is Neupogen® given?

According to the FDA-approved drug label, the treatment plan for patients acutely exposed to myelosuppressive doses of radiation (hematopoietic syndrome of the acute radiation syndrome) is to give 10 micrograms per kilogram of patient weight (10 mcg/kg) daily by subcutaneous injection. Neupogen® should be administered as soon as possible after suspected or confirmed exposure to radiation doses greater than 2 gray (Gy).

It is recommended in the FDA-approved drug label that clinicians obtain a baseline Complete Blood Count (CBC):

Obtain a baseline Complete Blood Count (CBC) followed by serial CBCs approximately every third day until the absolute neutrophil count (ANC) remains greater than 1,000/mm3 for three consecutive CBCs. Do not delay administration of Neupogen® if a CBC is not readily available. Discontinue Neupogen® therapy until the ANC remains greater than 1,000/mm3 for three consecutive CBCs or greater than 10,000/mm3 after a radiation-induced nadir. The safe use of Neupogen® and duration of Neupogen® treatment will require periodic monitoring of ANC levels as resources permit. For additional information, refer to the Neupogen® package insert.

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What are the side effects of Neupogen®?

The most common side effect of Neupogen® is mild to moderate bone pain that may require an analgesic. Other possible side effects of Neupogen® include fever, diarrhea, skin rash and weakness.

Enlargement and rupture of the spleen can rarely occur in patients who are receiving Neupogen®. Patients who develop abdominal pain, particularly in the left side, or left shoulder pain while receiving the drug should be evaluated as soon as possible.

Certain serious conditions have been reported in patients receiving Neupogen® such as sickle cell crisis, acute respiratory distress syndrome, splenic ruptures, glomerulonephritis, alveolar hemorrhage and hemoptysis, capillary leak syndrome, thrombocytopenia, leukocytosis, cutaneous vasculitis, and serious allergic reactions (i.e., anaphylaxis). If any of these conditions are present, discontinue therapy.

For full information on warnings and precautions, please refer to the Neupogen® package insert

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Where can I get Neupogen®?

Neupogen® is commercially available in the marketplace and should be used according to the FDA-approved label in patients who have been exposed to high doses of radiation. Additionally, Neupogen® may be distributed through CDC’s Strategic National Stockpile (SNS) when local supplies are depleted or not readily available during an emergency.

In the event of a radiation public health emergency, more detailed information regarding Neupogen® and any emergency use instructions will be provided through state and local public health officials.

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Other information sources

Further information on Neupogen® and the hematopoietic sub-syndrome of the acute radiation syndrome can be found at the following links:

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