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Pegfilgrastim (Fulphila)

Pegfilgrastim (Fulphila)

What Is Pegfilgrastim?

Pegfilgrastim (pronounced [peg fil GRA stim]), which is also known by the brand name, Neulasta, is a hematopoietic agent that is used to treat neutropenia. Neulasta was the first medication produced based on the active element pegfilgrastim. Pegfilgrastim is not a hazardous drug, nor is it a form of chemotherapy.

Based on Neulasta, several different biosimilars have been produced, one of which is called Fulphila. Fulphila is similar to Neulasta in its mechanism of action, administration route, strength, and dosage.

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What Is a Biosimilar?

A biosimilar drug is a low-cost alternative to a biologic medicine that is similar but not identical to the original medicine. There is no clinical difference. Biosimilars are similar to the FDA-approved medicines in their potency, purity, safety, and efficacy and can be used interchangeably.

What Is Neutropenia?

Neutropenia occurs when you have too few neutrophils, a type of white blood cell that helps our bodies fight off infections. Having neutropenia indicates a higher risk of developing serious bacterial and fungal infections. Neutropenia is a very common side effect of cancer patients undergoing chemotherapy.

Febrile neutropenia is a more serious condition where the neutrophil count drops to a dangerously low level where there are not enough white blood cells to fight off infections. This could potentially lead to life-threatening infections.

Mechanism of Action

Pegfilgrastim is a blood cell colony-stimulating agent (CSA) and has been used successfully by cancer patients to stimulate the growth of white blood cells, more specifically neutrophils. It does this by stimulating the production of neutrophils directly from the bone marrow.

How Is Fulphila Used?

Fulphila has been approved by the Food and Drug Administration (FDA) for the treatment and prevention of (febrile) neutropenia caused by chemotherapy or radiation.

Available Formulations

Fulphila is only available as a subcutaneous (under the skin) injection. The injection is available as a single-use prefilled syringe for subcutaneous injection at a dose of 6 mg/0.6 mL. 

The injection sites can include upper areas of the buttocks, front of the thighs, lower abdomen area (2 inches away from the navel), or the upper outer arms. Do not inject into areas where the skin is tender, bruised, red, scaly, or hard, and avoid areas with scars or stretch marks. After injection, do not rub the injection site. Do not handle the prefilled syringe if you are allergic to latex, and do not save unused medication in the prefilled syringe for later use. You should not attempt to give yourself a subcutaneous injection until you have received the appropriate training from your healthcare provider.

Missed Dose

If you miss a dose, contact your physician immediately to reschedule.

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Store Fulphila in the refrigerator and avoid freezing. If frozen, thaw in the refrigerator before use. Fulphila should be thawed (taken out of the refrigerator) for 30 minutes at room temperature before injecting. It can be left at room temperature for up to 72 hours. Do not shake the vials and keep them protected from light by storing them in their original containers.


Dispose of Fulphila if it has been left at room temperature for more than 72 hours. Dispose of Fulphila if it has been frozen more than once. After injection, dispose of any unused Fulphila left in the prefilled syringe. Be sure to dispose of the pre-filled syringes in an FDA-cleared sharps disposal container (not in the household trash).

What To Avoid While Taking Pegfilgrastim

While on the pegfilgrastim therapy, you must follow some precautions. Always tell your physician about any medications you are already taking. Do not take any drug or medicine (even herbals or over-the-counter medications) without prior consent from your physician or pharmacist, as they may have interactions with Fulphila. Avoid taking Fulphila within 14 days before or 24 hours after having chemotherapy.

Pregnancy and Fulphila

Pregnant women, women who are planning to become pregnant, and breastfeeding women must consult a physician prior to initiating Fulphila. The risk to the fetus or baby is unknown.

Side Effects

As with any other medication, you may encounter side effects while taking pegfilgrastim. A few things to keep in mind are:

  • You may not have all the side effects listed below. Many people may experience little to no side effects.
  • The severity of side effects may vary from person to person, so do not compare your side effects with other people’s experiences.
  • Most of the side effects will improve when therapy is discontinued.
  • Do not hide any symptoms; when you feel any discomfort, do not hesitate to tell your physician or pharmacist about it.

Note: The side effects listed below are not a comprehensive list of all side effects. Talk to your doctor if you have questions. 

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Some of the more serious side effects of Fulphila are:

Injection-site Pain

Most needles are painful, but Fulphila is especially known for causing some pain in the injection site, even for a while after the injection is complete. This is also often accompanied by mild bruising, swelling, or redness at the injection site.

Injection site pain can be controlled using over-the-counter painkillers such as Tylenol or Motrin, but usually, they resolve on their own within a few days. Consult your doctor or pharmacist prior to starting any new over-the-counter therapies.

Bone and Muscle Aches

This is the most common side effect of Fulphila since it stimulates the bone marrow (a spongy substance found inside of bone), causing it to swell and cause potential bone pain. It commonly starts about 1 to 2 days after receiving a Fulphila dose and can last up to a week, depending on the person.

Bone or muscle pains can be controlled using over-the-counter painkillers such as Tylenol or Motrin. Consult your doctor or pharmacist before starting any new over-the-counter therapies.

Thrombocytopenia, Leukocytosis

It is essential to keep up with regular blood tests, especially the complete blood count test (CBC). The CBC blood test is capable of detecting potential side effects of Fulphila, including leukocytosis (high white blood cells level) and thrombocytopenia (low platelet count). Contact your physician if any unusual bleeding or bruising occurs.

Lung Problem Called Acute Respiratory Distress Syndrome (ARDS)

Contact a physician or get emergency medical help right away if you have shortness of breath with or without a fever, trouble breathing, or a fast rate of breathing.

Kidney Injury

Call your doctor right away if you experience puffiness in your face or ankles, blood in your urine, or brown-colored urine. Also, contact your doctor if you notice you urinate less than usual.

Capillary Leak Syndrome (CLS)

Fulphila can cause fluid to leak from blood vessels into your body’s tissues. CLS can quickly cause you to have symptoms that may become life-threatening. Get emergency medical help right away if you develop any of the following symptoms: swelling or puffiness, urinating less often, trouble breathing, swelling of the abdominal area, and feeling of fullness, dizziness, or faintness.

Inflammation of Blood Vessels

Contact your physician if you develop purple spots or redness on your skin.

Rupture of the Spleen

A ruptured spleen is one of the most severe side effects of Fulphila. The spleen may become enlarged and may possibly rupture, which can be fatal. Call your doctor right away if you have pain in the upper left stomach (abdomen) or your left shoulder.

Less severe side effects can include:

  • Sweating
  • Dark urine

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Unless approved by your physician, pegfilgrastim is generally not recommended for:

  • Patients who have an allergy to human granulocyte colony-stimulating factors (CFS) such as filgrastim or pegfilgrastim products. The needle cap on the prefilled syringe contains natural rubber (derived from latex). Do not handle the prefilled syringe if allergic to latex. Allergic reactions can cause a rash over the whole body, shortness of breath, wheezing, dizziness, swelling around your mouth or eyes, fast heart rate, and sweating. If you have any of these symptoms, stop using Fulphila and call your doctor or get emergency help right away.
  • Patients with sickle cell disorder. Using Fulphila can lead to a condition called sickle cell crisis, which may be life-threatening and require discontinuation of Fulphila.
  • Patients receiving radiation therapy. Fulphila may increase the risk of developing a precancerous condition called myelodysplastic syndrome (MDS) or a type of blood cancer called acute myeloid leukemia (AML).


Is Fulphila a chemo agent?

No, it is not a chemotherapy agent. Instead, it helps treat a major side effect of chemotherapy called neutropenia (low white blood cell count). Chemotherapy drugs are directed at combating your cancer cells, while Fulphila is designed to combat the after-effects of a chemotherapy session.

How is Fulphila taken?

Fulphila is only available as a pre-filled injection. It can be injected subcutaneously (under the skin). You should not attempt to give yourself a subcutaneous injection until you have received the appropriate training from your healthcare provider.


Pegfilgrastim. In: Lexi-drugs online [database on the Internet]. Hudson (OH): Lexicomp, Inc.; 2016 [updated 329 Oct 2021; cited 9 Nov 2021]. Available from:

Pegfilgrastim. In: In Depth Answers [database on the Internet]. Greenwood Village (CO): IBM Corporation; 2017 [cited 2021 Nov 9]. Available from:

Fulphila: Uses, dosage, side effects, warnings. (n.d.). Retrieved November 9, 2021, from

Fulphila. 2021. [online] Available at: <> [Accessed 9 November 2021].

This information is not a substitute for medical advice or treatment. Talk to your doctor or healthcare provider about your medical condition prior to starting any new treatment. AmeriPharma™ Specialty Care assumes no liability whatsoever for the information provided or for any diagnosis or treatment made as a result, nor is it responsible for the reliability of the content. AmeriPharma™ Specialty Care does not operate all the websites/organizations listed here, nor is it responsible for the availability or reliability of their content. These listings do not imply or constitute an endorsement, sponsorship, or recommendation by AmeriPharma™ Specialty Care. This webpage may contain references to brand-name prescription drugs that are trademarks or registered trademarks of pharmaceutical manufacturers not affiliated with AmeriPharma™ Specialty Care.

Dr. Dania Jaradat, PharmD was born and raised in Torrance, California. She graduated from Marshall B. Ketchum University. The most rewarding part of her job is to keep the line between pharmacist and patient open and to educate patients on medication management. In her free time, she enjoys traveling to different countries, spending time with her husband and son, and reading. See Author Biography

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