Does Lurbinectedin Pass into Breast Milk?
Lurbinectedin, a chemotherapy agent used for small cell lung cancer, is not recommended during breastfeeding. It likely passes into breast milk due to its low molecular weight (around 750 Da) and high plasma protein binding, which allow excretion into milk. No direct human studies measure its levels in breast milk, but animal data and pharmacokinetics suggest exposure risk to nursing infants.[1]
What Happens If an Infant Is Exposed?
Infants could face severe risks from lurbinectedin in milk, including myelosuppression (low blood cell counts), gastrointestinal toxicity, and potential long-term developmental harm. The drug inhibits DNA repair, which could damage rapidly dividing infant cells. Case reports for similar alkylating agents show infant neutropenia and death after maternal exposure.[2][3]
Official Guidance on Breastfeeding
FDA labeling for Zepzelca (lurbinectedin) advises against breastfeeding during treatment and for at least 2 weeks after the last dose. This accounts for the drug's half-life (about 50 hours) and time for milk clearance. LactMed database recommends pumping and discarding milk during therapy plus this washout period.[1][4]
How Long to Wait Before Resuming Breastfeeding?
Wait a minimum of 2 weeks post-infusion, based on 5 half-lives for near-complete elimination. Monitor infant for signs of toxicity if accidental exposure occurs, such as lethargy, poor feeding, or infection. Consult oncology and lactation specialists for individualized timing.[4]
Alternatives for Mothers on Lurbinectedin
Use formula feeding or donor milk during treatment. Pumping maintains supply without infant risk. No safe "pump and dump" threshold exists due to unknown milk concentrations.[4]
Sources
[1]: FDA Zepzelca Label
[2]: Drugs.com Lurbinectedin Monograph
[3]: LactMed: Lurbinectedin
[4]: LactMed Summary on Chemotherapy Agents