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Treatment Name: Filgrastim (Neupogen®, Zarxio®, Nivestym®, Releuko®)

Filgrastim (Neupogen®, Zarxio®, Nivestym®, Releuko®) is a Supportive Care Therapy to prevent or treat Neutropenic Fever

How does filgrastim work?
Filgrastim is designed to lower risk of infection after chemotherapy. It is part of a family of drugs called “granulocyte colony-stimulating factor” (G-CSF), or growth factor.

Filgrastim binds to bone marrow stem cells to speed up production of certain white blood cells known as neutrophils. Neutrophil white blood cells are part of your immune system. Chemotherapy kills fast growing cells such as cancer cells, but sometimes kills good cells such as neutrophils too. When this happens, it is called neutropenia, a sign that your immune system is weakened and low in neutrophils.

Neutrophils are some of the first responders to infection. In a normal immune system, neutrophils cause swelling, redness, and itching at the site of infection. After chemotherapy, neutrophils die and do not cause the same symptoms of infection. Fever may be one of the only signs of infection.

When neutrophils become low and you have a fever, it is called neutropenic fever. Neutropenic fever is a medical emergency. Fevers after chemotherapy should be reported to a doctor immediately or patients should report to a hospital emergency department.

Goals of therapy:
Filgrastim is used to keep the neutrophil count from declining to unsafe levels after certain chemotherapy regimens are given, specifically those having a high risk of neutropenic fever. This lowers the risk of neutropenic fever, but does not prevent it all of the time.

When filgrastim is taken to prevent neutropenic fever, it is known as prophylaxis, or prophylactic therapy. On occasion, filgrastim is given as prophylaxis to patients who have a low neutrophil count from reasons other than chemotherapy. If you develop neutropenic fever, filgrastim may also be used to help treat neutropenic fever in certain situations.

Filgrastim is also used for those undergoing a stem cell transplant, commonly known as a “bone marrow transplant” (BMT). Filgrastim is used to produce the extra stem cells needed for collection before transplant. It may also be used at least 24 hours after certain types of transplants to help increase the likelihood of engraftment.


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Filgrastim is usually injected under the skin (subcutaneous injection) at home or in the clinic. If your prescription insurance does not cover filgrastim injections as a prescription, you may have to receive them from a home health agency or go in to the clinic or infusion room daily.

  • Filgrastim is supplied in vials or prefilled syringes, which contain 300 mcg or 480 mcg of drug
  • If injecting this yourself at home, filgrastim should be stored in the refrigerator between 2° to 8° C (36° to 46° F). Avoid freezing filgrastim and protect it from light. You may remove it from the fridge 30 min before injecting to allow it to reach room temperature. Filgrastim should not be allowed to remain at room temperature for more than 24 hours
  • Possible injection sites include: outer area of upper arms, abdomen (either side of belly-button, but not within 2 inches of belly button), thighs, or upper outer area of the buttock
  • Filgrastim is usually given in the outpatient setting roughly 24 hours after the end of chemotherapy to prevent neutropenic fever. Since filgrastim is a short-acting growth factor, you will likely need to get an injection every day for a period of time that is determined by your doctor.
  • If you miss a dose, talk with your healthcare provider about when you should take the next dose

Filgrastim is generally used for patients with curable cancers whose chemotherapy carries more than a 1 in 5 (20%) chance of developing neutropenic fever. It may also be used for lower risk chemotherapy in patients who have weak immune systems, poor organ function, or a history of low neutrophil count or neutropenic fever. When initially prescribed, filgrastim is usually repeated at the end of every chemotherapy cycle.

Usual Filgrastim starting dose after chemotherapy:

  • Filgrastim 5 mcg/kg injection under the skin Once Daily

For those undergoing stem cell collection for a future transplant, the dose of filgrastim is higher. Filgrastim is often started at least 4 days before the first day of planned stem cell collection for autologous stem cell transplants. After the bone marrow transplant occurs, filgrastim may be restarted 24 hours or more after the stem cell infusion.

Usual Filgrastim starting dose for blood and marrow transplant (BMT):

  • Filgrastim 10 mcg/kg injection under the skin Once Daily

Side Effects

In clinical studies, the most commonly reported side effects of filgrastim are shown here. The exact percentages of patients that will experience filgrastim side effects is unknown because it has been used under widely varying patient populations in a variety of clinical trials:

  • Bone pain (up to 26%)
  • Back pain (up to 15%)
  • Rash (up to 14%)
  • Shortness of breath or cough (up to 14%)

Roughly 4% of patients discontinue Filgrastim due to unacceptable side effects.

Splenic rupture, although extremely rare, has occurred in patients taking filgrastim. After taking filgrastim, patients should tell their doctor if they have left upper abdomen pain or left shoulder pain from an enlarged spleen.

If a fever develops, it may be from chemotherapy or the underlying condition being treated. Filgrastim is designed to prevent a fever and does not usually cause fever. If fever occurs, also report the following signs or symptoms to your doctor immediately: shortness of breath, (with or without fever), allergic reaction, swelling, changes in urination or color of urine, or skin changes.

Side effect videos Side Effect Videos
Neutropenic FeverNeutropenic FeverPainPain


How often is monitoring needed?
Labs (blood tests) may be checked on the day of chemotherapy. If you develop fevers, labs will need to be drawn again to see if your “absolute neutrophil count” (ANC) is low. If your ANC is low, you may need to have blood cultures or other labs done to look for infection. Labs may be checked daily until neutrophils recover to a safe level. Labs often include: Complete Blood Count, plus any others your doctor may order.

How might blood test results/imaging affect treatment?
Depending upon the results, your doctor may advise to continue filgrastim as planned, reduce the dose of future treatments, delay the next dose of filgrastim until a side effect goes away, or switch to an alternative therapy.

After receiving filgrastim, some patients may see the white blood cell count (WBC) temporarily rise to above 100,000/mm3. This is not usually associated with any adverse clinical effects other than bone pain, and returns to normal shortly after the last dose of filgrastim is given.

Filgrastim dose adjustment for patients with liver or kidney problems is not necessary.

Questions to Ask Your...

A better understanding of your treatments will allow you to ask more questions of your healthcare team. We then hope that with the answers, you will get better results and have greater satisfaction with your care. Because we know it's not always easy to know what questions to ask, we've tried to make it easy for you!

Choose any healthcare provider below to see common questions that you may want to ask of this person. Then, either print each list to bring to your clinic visits, or copy the questions and send them as a message to your healthcare team through your electronic medical record.

ChemoExperts Tips

  • Filgrastim is usually used to shorten the time neutrophils are low after chemotherapy with a high risk (at least 1 in 5 chance) of causing neutropenic fever
  • If you develop neutropenic fever, you will need to be given “broad spectrum” antibiotics until your ANC rises to a safe level. Antibiotics are most often intravenous, given in a hospital setting
  • Neutropenic fever most commonly happens 1 to 2 weeks after receiving chemotherapy. Make sure to have a working thermometer at home so you can check your temperature
  • After chemotherapy, it is important to watch for fevers. Call your oncology clinic immediately or go to the nearest emergency department if you have any temperature of 101° F (38.3° C) or above, or any temperature of 100.4° F (38° C) or above that stays elevated for over one hour
  • Tell your doctor if you have sickle cell anemia as special precautions may need to be taken
  • Tell your doctor if you have a latex allergy since the prefilled syringe has a natural rubber needle cap. The vial, instead of the syringe, may be recommended for patients with latex allergy
  • Although no drug interactions with filgrastim are currently known, a pharmacist should ALWAYS review your medication list to ensure that drug interactions are prevented or managed appropriately
  • If taking filgrastim at home, be sure to have all of your questions answered by your doctor or pharmacist regarding the proper dose and administration technique. Also, if your doctor recommends a dose other than the entire contents of a syringe or vial, be sure to discuss with them how this is best accomplished. Your pharmacist can advise you on the proper way to dispose of used filgrastim syringes
  • If filgrastim is needed during pregnancy, the potential benefit of the mother taking filgrastim should be weighed against the potential harm to the baby. Your doctor should help you with this decision. Additionally, it is not known if filgrastim enters human breast milk. If you are breastfeeding and are advised to take filgrastim, talk to your doctor about ways to decrease risk of drug exposure to the baby.

Patient Assistance & Co-payment Coverage

Patients under the age of 65 years, or those with private insurance plans:
If you have insurance and are looking for patient assistance or copay assistance for Filgrastim (Neupogen®, Zarxio®, Nivestym®, Releuko®), we have provided links that may help.

Visit our Patient Assistance page and click the links to various patient assistance programs for help paying for Filgrastim (Neupogen®, Zarxio®, Nivestym®, Releuko®). Depending upon your income, they may be able to help cover the cost of:

  • Filgrastim (Neupogen®, Zarxio®, Nivestym®, Releuko®)

For Branded medications (may be available for generic medications too), check with the manufacturer to determine if a co-pay card is offered and if it could reduce your monthly copay.

  • If you are uninsured, check with the manufacturer to determine if you are eligible to receive medication at no cost.

Medicare and Medicaid patients (Patients 65 years or older):
The clinic providing treatment will likely pre-authorize medications and immune therapies such as Filgrastim (Neupogen®, Zarxio®, Nivestym®, Releuko®) and are the best source to help you understand drug cost.

  • Ask to speak with a patient assistance technician or financial counselor at the clinic or hospital administering this therapy.

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Filgrastim package insert.

Created: November 9, 2017 Updated: November 13, 2018

What is Neutropenic Fever?

Neutropenia is when you have a low number of infection fighting cells in your blood called neutrophils.

A fever is when someone has a single temperature of 101°F or higher or a temperature of at least 100.4°F that does not go away after one hour. When someone develops a fever at the same time they have low neutrophils, they are considered to have a "neutropenic fever." This is also sometimes called "febrile neutropenia."

Unless told otherwise by their doctor, someone with neutropenic fever should get to the emergency room IMMEDIATELY! Do NOT wait! Without proper treatment, neutropenic fever can cause life-threatening symptoms within a matter of hours. Fever may be one of the only signs of infection, therefore it is very important that you have a thermometer if you are receiving chemotherapy.

NOTE: Treatment Options listed below are not all-inclusive. Other treatments may be available. ChemoExperts provides drug information and does not recommend any one treatment over another. Only your Doctor can choose which therapy is appropriate for you.

What is neutropenia?

This occurs when there is an abnormally low amount of a certain type of white blood cells, called neutrophils, in the blood. Neutrophils help the body fight infections caused by bacteria and viruses. Many chemotherapy drugs temporarily damage bone marrow where white blood cells are created, resulting in neutropenia. Please watch our video on neutropenic fever to learn more.