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Generic name: pegfilgrastimPEG-fil-GRAS-tim ]
Brand names: Fulphila, Fylnetra, Neulasta, Neulasta Onpro Kit, Nyvepria, ... show all 8 brands
Drug class: Colony stimulating factors

Medically reviewed by on Jan 13, 2023. Written by Cerner Multum.

What is Ziextenzo?

Ziextenzo is used to prevent neutropenia (a lack of certain white blood cells) that is caused by receiving chemotherapy.

Ziextenzo is a form of a protein that stimulates the growth of white blood cells that help your body fight against infection.

Ziextenzo may also be used for purposes not listed in this medication guide.


Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Before taking this medicine

You should not use Ziextenzo if you are allergic to Ziextenzo or filgrastim (Neupogen).

Tell your doctor if you have ever had:

Treatment with Fulphila and radiation with or without chemotherapy for breast or lung cancer, you could develop a blood disorder or blood cancer (leukemia). Ask your doctor about this risk.

Tell your doctor if you are pregnant or breastfeeding.

How should I use Ziextenzo?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed. Ziextenzo should not be given within 14 days before or 24 hours after you receive chemotherapy.

Ziextenzo is injected under the skin. A healthcare provider may teach you how to properly use the medication by yourself.

Read and carefully follow any Instructions for Use provided with your medicine. Ask your doctor or pharmacist if you don't understand all instructions.

Prepare your injection only when you are ready to give it. Do not use if the medicine looks cloudy, has changed colors, or has particles in it. Call your pharmacist for new medicine.

Your blood may need to be tested often.

Carefully follow your doctor's instructions when giving Ziextenzo to a child who weighs less than 99 pounds (45 kilograms). The correct dose for a child this size cannot be accurately measured using the prefilled syringe.

You may need medical tests to help your doctor determine how long to treat you with Ziextenzo.

Store the prefilled syringe in its original package in the refrigerator, protected from light. Do not shake or freeze.

Take the syringe out of the refrigerator and let it reach room temperature for 15 to 30 minutes before injecting your dose. If a syringe has become frozen, thaw it in a refrigerator. Do not use any syringe that has been frozen more than one time.

Do not use a Neulasta or Udenyca syringe that has been left at room temperature for longer than 48 hours. Do not use a Fylnetra, Fulphila, o Stimufend syringe that has been left at room temperature for longer than 72 hours. Do not use a Ziextenzo syringe that has been left at room temperature for longer than 5 days.

The Neulasta Onpro Injector is a special device placed on the skin that delivers your Ziextenzo dose at a specific time. You will need to wear the device for 27 hours before the dose begins. The timed dose will then be released from the device slowly over a 45-minute period.

Keep Neulasta Onpro refrigerated until you are ready to wear it. Do not use an Neulasta Onpro device that has been left out of a refrigerator for longer than 12 hours. Do not use Nyvepria prefilled syringe that has been left out of the refrigerator for longer than 15 days.

While wearing Neulasta Onpro, you or a caregiver will need to check the device to make sure it is working properly.

Each prefilled syringe or Onpro Injector is for one use only. Throw it away after one use, even if there is still medicine left inside.

Use a needle and syringe only once and then place them in a puncture-proof "sharps" container. Follow state or local laws about how to dispose of this container. Keep it out of the reach of children and pets.

What happens if I miss a dose?

Call your doctor for instructions if you miss an injection, or if you have a problem with the Neulasta Onpro device.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms include bone pain, pain when you breathe, feeling short of breath while lying down, wheezing, gasping for breath, cough with foamy mucus, cold, clammy skin, anxiety, rapid heartbeats.

What should I avoid while using Ziextenzo?

When using Neulasta Onpro: Avoid traveling, driving, or operating machinery while wearing the device.

Ziextenzo side effects

Get emergency medical help if you have signs of an allergic reaction: hives, skin rash, sweating, warmth or tingly feeling; dizziness, fast heartbeats; wheezing, difficulty breathing; swelling of your face, lips, tongue, or throat.

Capillary leak syndrome is a rare but serious side effect of pegfilgrastim. Call your doctor right away if you have signs of this condition, which may include: decreased urination, tiredness, dizziness or light-headed feeling, trouble breathing, and sudden swelling, puffiness, or feeling of fullness.

Ziextenzo may cause serious side effects. Call your doctor at once if you have:

  • sudden or severe pain in your left upper stomach spreading up to your shoulder;

  • sudden and severe pain in your chest, stomach, or back;

  • severe or ongoing pain anywhere in your body;

  • fever, tiredness;

  • shortness of breath, rapid breathing;

  • easy bruising, unusual bleeding, purple or red spots under your skin;

  • bruising, swelling, or a hard lump where the medicine was injected; or

  • kidney problems--little or no urination, pink or dark urine, swelling in your face or lower legs.

Your cancer treatments may be delayed or permanently discontinued if you have certain side effects.

Common side effects of Ziextenzo may include:

  • bone pain; or

  • pain in your arms or legs.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Ziextenzo?

Other drugs may affect Ziextenzo, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Where can I get more information?

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Frequently asked questions

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.