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Neulasta: 7 things you should know

Medically reviewed by Carmen Pope, BPharm. Last updated on Sep 22, 2023.

1. How it works

  • Neulasta is a brand (trade) name for pegfilgrastim which may be used to prevent neutropenia. The actual active ingredient in Neulasta is filgrastim, but this has been 'pegylated' (attached to a chemical called polyethylene glycol) which slows down the removal of filgrastim from the body, allowing it to be given less frequently. This is why it is called pegfilgrastim.
  • Filgrastim is a man-made substance that resembles a human protein called granulocyte colony-stimulating factor (G-CSF). Filgrastim is the active part of Neulasta, and it works by binding to specific cell surface receptors on hematopoietic cells (these are immature blood cells), stimulating the production, maturation, activation, and release of neutrophils from the bone marrow. This increases white blood cell counts and treats neutropenia. White blood cells are crucial for the immune system to fight infection.
  • Neulasta (pegfilgrastim) belongs to the class of medicine known as colony-stimulating factors.

2. Upsides

  • Neulasta may be used to reduce the risk of infection in those people with cancer (other than myeloid leukemias) receiving bone marrow-suppressing anti-cancer drugs that are highly likely to cause febrile neutropenia. Febrile neutropenia is fever (and often other signs of infection) associated with abnormally low numbers of neutrophils (a type of white blood cell).
  • Neulasta boosts the production of infection-fighting white blood cells and helps to prevent neutropenia caused by chemotherapy.
  • May also be used to increase survival in patients acutely exposed to bone marrow-suppressing doses of radiation.
  • Neulasta contains pegylated filgrastim (pegfilgrastim) which means it lasts for longer in the body than unpegylated filgrastim, such as Neupogen.
  • Neulasta is usually given once per chemotherapy cycle.
  • The dosage in adults is one single subcutaneous injection of 6 mg administered once per chemotherapy cycle, at least 24 hours after the chemotherapy and at least 14 days before the next cycle. The dosage for children weighing less than 45kg is weight-based (refer to the product information).
  • Available as a single-dose prefilled syringe for administration by a health professional or for use with the on-body injector (OBI) for Neulasta, which is co-packaged with a single-dose prefilled syringe. The dose of Neulasta is delivered subcutaneously (under the skin). Some people or caregivers may be taught how to administer the injections at home.
  • Neulasta is available as a generic under the name pegfilgrastim.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • Bone pain, skeletal pain, and medullary bone pain are the most common side effects reported, occurring in up to 30% to 49% of people. Because Neulasta works within the bone marrow, it is these changes that also cause the side effects of bone pain, skeletal pain, and medullary bone pain. Neulasta is thought to cause bone pain by affecting bone marrow expansion and bone metabolism, sensitizing the peripheral nerve, and releasing histamine which can cause inflammation and local swelling.
  • Elevations in laboratory test results for lactate dehydrogenase, alkaline phosphatase, and uric acid have been reported in up to 20% of people. High white blood cell (WBC) counts of 100 x (10)9/L or greater have been observed in patients receiving pegfilgrastim. Monitoring of complete blood count (CBC) during pegfilgrastim therapy is recommended.
  • The length of time side effects last varies. Peak levels of Neulasta are reached 24 hours after injection, then levels drop considerably over the first 7 days and after 14 days there is only a small amount remaining in the body. Side effects are more likely to occur when the medicine is at its highest blood level.
  • Neulasta has been associated with splenic rupture, some of which have been fatal. Investigate all patients who report abdominal or shoulder pain for an enlarged spleen or splenic rupture. Neulasta may also cause acute respiratory distress syndrome (ARDS) can occur in patients receiving Neulasta. Evaluate patients who develop fever and lung infiltrates or respiratory distress after receiving Neulasta, for ARDS. Discontinue Neulasta in patients with ARDS.
  • Capillary leak syndrome has also been reported after Neulasta administration, symptoms include low blood pressure, hypoalbuminemia, edema, and hemoconcentration, which can range from mild to severe and may be life-threatening if treatment is delayed. Closely monitor patients and consider intensive care if they develop symptoms. Aortitis (inflammation of blood vessels) has also been reported.
  • Because the granulocyte colony-stimulating factor (G-CSF) receptor through which Neulasta acts has been found on cancer cells, there is a possibility that Neulastic may increase the growth of cancerous cells.
  • Not to be used for the mobilization of peripheral blood progenitor cells for hematopoietic stem cell transplantation.
  • Be cautious when using in people with sickle cell disorders. Severe and sometimes fatal sickle cell crises can occur in patients in those with sickle cell disorders who receive pegfilgrastim products. Discontinue Neulasta if a sickle cell crisis occurs. Glomerulonephritis has also occurred which usually resolves on dose reduction or Neulasta discontinuation.
  • Use of the OBI for Neulasta is not recommended for patients with Hematopoietic Subsyndrome of Acute Radiation Syndrome and its use has also not been studied in children. Use the manual pre-filled syringe instead.
  • Neulasta must be administered (or the OBI system set up) by a health professional. People cannot be taught how to self-administer Neulasta.
  • Neulasta should be removed from the refrigerator before use at between 36°F to 46°F (2°C to 8°C) and allowed to reach room temperature for a minimum of 30 minutes. Neulasta that has been left at room temperature for more than 12 hours (Neulasta Onpro kit) or 48 hours (prefilled syringe) and not used should be thrown away in an FDA-approved sharps bin.
  • Should not be given to people with a previous reaction to Neulasta, pegfilgrastim, filgrastim, or any of the other substances in the syringe.
  • People with latex allergies should not administer Neulasta because the needle cap on the prefilled syringes contains dry natural rubber derived from latex.
  • Neulasta cannot be administered within 24 hours of chemotherapy. The Neulasta OBI is designed so that it starts delivering Neulasta 27 hours after it has been applied to the patient's skin. A healthcare provider must fill the OBI with Neulasta using the prefilled syringe and then apply the OBI for Neulasta to intact, non-irritated skin on the patient’s abdomen or back of their arm. However, the back of the arm may only be used if there is a caregiver available to monitor the status of the OBI for Neulasta. Once the OBI starts delivering Neulasta, it delivers it over approximately 45 minutes.
  • If a patient misses a dose due to an OBI for Neulasta failure or leakage, administer a new dose by single-dose prefilled syringe for manual use, as soon as possible after detection.
  • Health providers should only use the prefilled syringe co-packaged in the Neulasta Onpro® kit with the OBI for Neulasta. This prefilled syringe contains an additional solution to compensate for liquid loss during delivery through the OBI for Neulasta. If this prefilled syringe was to be used for a manual injection, it would result in the patient receiving an overdose. If the single-dose prefilled syringe for manual use is used with the OBI for Neulasta, the patient may receive less than the recommended dose.
  • The OBI for Neulasta should NOT be used to deliver any other drug product except the Neulasta prefilled syringe co-packaged with the OBI for Neulasta.
  • Because of the way Neulasta acts, imaging studies may report transient positive bone imaging changes. Consider this when interpreting bone imaging results.
  • There is a lack of data regarding the use of Neulasta during pregnancy; however, what data is available has not established an association of any filgrastim product use during pregnancy with major birth defects, miscarriage, or adverse maternal or fetal outcomes. Filgrastim products are secreted poorly into breast milk, and filgrastim products are not absorbed orally by neonates, but the benefits of breastfeeding need to be weighed up against the risks of Neulasta.
  • The safety and effectiveness of Neulasta has not been established in children. No overall differences in safety or effectiveness have been observed between patients aged 65 and older and younger patients.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Neulasta injection is a prescription medicine that may be given once every chemotherapy cycle to prevent febrile neutropenia in those people at high risk of it because of cancer treatments they are receiving or from radiation. Neulasta needs to be given no less than 24 hours after chemo and at least 14 days before the next dose. It is available as an on-body injector (OBI) which a health professional can set up and which will deliver a dose of Neulasta 27 hours after the OBI has been placed on the skin over 45 minutes.

5. Tips

  • When you are undergoing chemotherapy for cancer, it is common for levels of certain white blood cells (such as neutrophils) to decrease. A decrease in neutrophils makes you more susceptible to infections. Neulasta helps to increase neutrophil levels and helps reduce this infection risk.
  • Bone and bone-related pain are the most common side effects of Neulasta, affecting up to one-third to half of all people prescribed Neulasta. This usually starts within two days of administration, with most people reporting the most painful day as day 3, with the pain gradually improving from day 4 onwards although it may last up to 8 days or longer.
  • If you have been prescribed loratadine (eg, Claritin) for bone pain, the usual dosage is one 10mg tablet once daily in the morning for 5 days, starting on the day Neulasta is given. Claritin is thought to help some of the bone pain caused by Neulasta by blocking histamine, which Neulasta also releases. Histamine can cause inflammation and swelling in the bone marrow. Studies have shown mixed results regarding how effective Claritin is for bone pain but it is well-tolerated, inexpensive, and easily administered, so may be considered.
  • See your doctor immediately if you develop any abdominal pain, shortness of breath, fever, swelling, low blood pressure, fainting when standing up, or other worrisome side effects.
  • If your doctor administers Neulasta through the Neulasta on-body injector, it starts delivering the Neulasta dose 27 hours after the on-body injector has been applied to the skin. When the Neulasta on-body injector is delivering the dose the green light will be rapidly flashing and the delivery process takes about 45 minutes to complete. You can remove the on-body injector when the Neulasta dose delivery is finished, which is when there has been a long beep and the status light is a solid green with NO flashing, or the status light has switched off. The best way to remove the Neulasta on-body injector is to grasp the edge of the adhesive pad and slowly peel the on-body injector away from the skin. Do NOT grab the on-body injector and try to pull it away from the skin. Once you have removed the on-body injector it is a good idea to inspect the device for any sign of leakage or if the adhesive is wet, as the device may have malfunctioned. If there is any sign of leakage you may not have received the full amount of Neulasta and a replacement dose may be required, therefore it is important to contact your healthcare provider immediately. The Neulasta OBI should be disposed of in an FDA-approved sharps disposal container as it contains a needle.
  • Avoid activities such as traveling, driving, or operating heavy machinery for 26 to 29 hours after the OBI for Neulasta has been applied. This includes the 27-hour waiting time, the 45-minute delivery period, plus an hour post-delivery. If it is your first time experiencing the OBI for Neulasta, you should have someone stay with you for this period. Always call your doctor immediately if you experience something untoward with the OBI for Neulasta or if the delivery fails, as you may need a replacement dose.
  • It is possible to have a short shower while you have the Neulasta OBI in place on your skin but you should avoid getting the on-body injector overly wet, using soap near or on the on-body injector, be careful that you don’t knock the on-body injector and dislodge the on-body injector, pat dry the area carefully, do NOT rub the area, and do NOT dry with a heat source. Time your shower so the on-body injector is dry for at least 3 hours before it is time to administer the Neulasta. Avoid using bathtubs, hot tubs, whirlpools, or saunas.
  • Avoid getting body lotions, creams, and oils near or on the on-body injector as these products may loosen the adhesive.
  • Do not expose the OBI for Neulasta to temperatures below 41°F (5°C) or above 104°F (40°C).
  • Keep the OBI for Neulasta at least 4 inches away from electrical equipment such as cell phones, cordless telephones, microwaves, and other common appliances. Failure to do so may interfere with its operation and can lead to a missed or incomplete dose of Neulasta.
  • Avoid airport X-ray scans and request a manual pat-down instead but ask the security officer to kindly not dislodge the Neulasta OBI during the pat-down process.
  • Avoid sleeping or applying pressure to the OBI for Neulasta as this may affect its performance.
  • Some people may develop allergic reactions to the acrylic adhesive used by the on-body injector (OBI). See your doctor if this happens to you.

6. Response and effectiveness

  • Once administered, Neulasta takes 16 to 120 hours (an average of 24 hours) to reach its peak concentration. Neulasta is a long-lasting medication so blood levels slowly decrease over approximately 2 weeks.
  • Neulasta’s effect of increasing neutrophil levels starts to kick in on the first day of the injection and neutrophil levels reach a peak at the same time as Neulasta reaches peak serum levels, which is about 24 hours after the Neulasta injection.
  • Once neutrophil levels have peaked, they start to decrease over the next 4 to 5 days due to the effect of chemotherapy. Neutrophils are usually at their lowest levels approximately 5 to 6 days after Neulasta injection depending on each person’s response. At around 6 days after the Neulasta injection, neutrophil levels start to increase once again.
  • Peak neutrophil levels are 24 hours (approximately) after a Neulasta injection, the lowest neutrophil levels are 5 days (approximately) after a Neulasta injection, and neutrophil levels start increasing again approximately 6 days after a Neulasta injection.
  • For Neulasta to have its best effect, it needs to go into the body 24 to 72 hours after chemotherapy. The Neulasta On-body Injector is applied to the skin usually on the same day as chemotherapy, it is designed to automatically start dispensing the Neulasta 27 hours from the time it was applied and it is slowly released over 45 minutes.
  • Two studies that involved 467 patients with breast cancer found Neulasta administered as a single dose to be just as effective as multiple daily injections of filgrastim. In both studies, the patients had severe neutropenia for around 1.7 days during their first chemotherapy cycle. This compares to around five to seven days when no stimulating factor is used.

7. Interactions

Medicines that interact with Neulasta may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with Neulasta. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with Neulasta include:

  • biologics, such as adalimumab, etanercept, golimumab, or infliximab
  • bleomycin
  • capecitabine, carboplatin, cyclophosphamide
  • cladribine
  • hydroxyurea
  • interferon or peginterferon
  • lithium
  • methotrexate
  • thalidomide.

Any medication that also increases the risk of infection has the potential to interact with Neulasta. Also if Neulasta is given too soon after chemotherapy, or too close before, it may potentially alter the way the chemotherapy works.

Note that this list is not all-inclusive and includes only common medications that may interact with Neulasta. You should refer to the prescribing information for Neulasta for a complete list of interactions.


Further information

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

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

Copyright 1996-2023 Revision date: September 22, 2023.