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When does Neulasta reach peak levels?

Medically reviewed by Melisa Puckey, BPharm. Last updated on July 17, 2023.

How long does it take for Neulasta (pegfilgrastim) to kick in?

Official answer


How long does it take for Neulasta to reach peak levels?

Once Neulasta (pegfilgrastim) is given as a subcutaneous injection the time it takes

  • to reach peak concentration ranges from 16 to 120 hours,
  • the median time to reach peak is approximately 24 hours.

Neulasta is a long lasting medication so blood levels slowly decrease over approximately 2 weeks.

How long does it take Neulasta to start increasing Neutrophil levels?

Neulasta’s effect of increasing neutrophil levels starts to kick in on the first day of the injection and neutrophil levels reach 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 day due to the effect of chemo. Neutrophils are usually at their lowest levels on approximately around 5 to 6 days after Neulasta injection depending on each person’s individual response. At around 6 days after the Neulasta injection neutrophils levels start to increase once again.

  • Peak neutrophils levels are 24 hours (approximately) after Neulasta injection
  • Lowest neutrophils levels are 5 days (approximately) after Neulasta injection
  • Neutrophils levels start increasing after 5 days (approximately) since Neulasta injection.

Related questions

When does Neulasta On-body Injector (OBI) deliver the medicine and how long does it take to go in?

For the 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 a 45 minute period.

Bottom line:

  • The median time for Neulasta to reach peak plasma levels is approximately 24 hours after injection, but ranges from 16 to 120 hours.
  • The time it takes Neulasta to induce peak levels of neutrophils is approximately 24 hours.
  • The time Neulasta On-body Injection delivers the medicine into the body is 27 hours after it has been applied and the Neulasta is released into the body over 45 minutes.

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