Eflornithine (Iwilfin™) is the first U.S. Food and Drug Administration–approved oral maintenance therapy for high-risk neuroblastoma. Approved in December 2023, eflornithine has an orphan drug designation.

This ONS resource was produced for educational purposes only. Refer to the eflornithine prescribing information for full details.

Classification Targeted therapy/enzyme inhibitor
Mechanism of Action Irreversible inhibition of the ornithine decarboxylase enzyme
Indication Reduces the risk of relapse in adult and pediatric patients with high-risk neuroblastoma who have demonstrated partial response to prior multiagent, multimodality therapy, including anti-GD2 immunotherapy
Dosing, Frequency, and Duration Dosing is based on body surface area (see prescribing information for full dosing instructions) and administered twice daily for up to two years or until patients experience disease progression or unacceptable toxicity. 
Route Oral
Safe Handling Eflornithine is a potentially hazardous drug per the National Institute for Occupational Safety and Health definition. Follow safe-handling precautions.
  • Hearing loss, otitis media
  • Pneumonia
  • Diarrhea
  • Pyrexia
  • Laboratory abnormalities: increased ALT and AST; decreased neutrophil count and hemoglobin
  • Myelosuppression 
  • Hepatotoxicity 
  • Hearing loss
  • Embryo-fetal toxicity
Pretreatment Obtain complete blood counts, liver function tests, pregnancy tests (as appropriate), and baseline audiograms.
Administration Instruct patients that they can take the medication with or without food and that the tablets may be swallowed whole, chewed, or crushed and mixed with two tablespoons of soft food or liquid. If they mix the medication in food, it must be consumed within an hour of mixing. 
During Treatment Monitor complete blood counts, liver function tests, and hearing.
  • Report signs of infection (e.g., fever, chills), easy bruising or bleeding, signs of anemia (e.g., shortness of breath, weakness), jaundice, light-colored stools, dark-colored urine, pain on the right side of the abdomen, and new or worsening hearing loss.
  • If you miss a dose, take it as soon as possible, but skip the missed dose if it is within seven hours of your next dose. 
  • If it is possible for you to concieve, use effective contraception during treatment and for one week after the final dose. Do not breastfeed or chestfeed during treatment and for one week after your final dose.
  • Store the medication at room temperature in a safe place away from children and pets. 
  • Eflornithine is also prescribed for other indications and in other formulations (e.g., topical cream); only use the medication as prescribed to you and as directed.
Patient Resources Patient-facing drug label
Healthcare Professional Resources Clinical trial report 
Prescribing information  
Other Resources National Cancer Institute A to Z List of Cancer Drugs page