Publication Details

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CASRN: 154361-50-9

image 135017419 in the ncbi pubchem database

Drug Levels and Effects

Summary of Use during Lactation

Most sources consider breastfeeding to be contraindicated during maternal antineoplastic drug therapy.[1] It might be possible to breastfeed safely during intermittent therapy with an appropriate period of breastfeeding abstinence. some have suggested a period of 24 hours before resuming nursing,[2] although the manufacturer recommends an abstinence period of 2 weeks. Capecitabine is metabolized to fluorouracil. Limited information indicates that a maternal continuous intravenous fluorouracil infusion at a dose of 200 mg/square meter daily produces undetectable levels in milk. If capecitabine use is undertaken, monitoring of the infant's complete blood count and differential is advisable. Chemotherapy may adversely affect the normal microbiome and chemical makeup of breastmilk.[3] Women who receive chemotherapy during pregnancy are more likely to have difficulty nursing their infant.[4]

Drug Levels

Capecitabine is a prodrug that is metabolized to fluorouracil.

Maternal Levels. A mother who was 9 months postpartum was diagnosed with rectal cancer and began treatment with pelvic radiotherapy and a continuous intravenous infusion of fluorouracil 200 mg/square meter daily. Her plasma fluorouracil concentration was constant at about 110 micromoles/L (14.3 mg/L) from weeks 2 to 5 of therapy. She discontinued nursing her infant and pumped her breasts twice daily and collected 36 breastmilk samples before, during and for 10 days following fluorouracil therapy (exact times not specified). Fluorouracil was undetectable (<0.5 micromole/L [<65 mcg/L]) in all of the milk samples.[5]

Infant Levels. Relevant published information was not found as of the revision date.

Effects in Breastfed Infants

Relevant published information was not found as of the revision date.

Effects on Lactation and Breastmilk

Relevant published information was not found as of the revision date.


Pistilli B, Bellettini G, Giovannetti E, et al. Chemotherapy, targeted agents, antiemetics and growth-factors in human milk: How should we counsel cancer patients about breastfeeding? Cancer Treat Rev. 2013;39:207–11. [PubMed: 23199900]
Johnson HM, Mitchell KB. ABM clinical protocol #34: Breast cancer and breastfeeding. Breastfeed Med. 2020;15:429–34. [PubMed: 32516007]
Urbaniak C, McMillan A, Angelini M, et al. Effect of chemotherapy on the microbiota and metabolome of human milk, a case report. Microbiome. 2014;2:24. [PMC free article: PMC4109383] [PubMed: 25061513]
Stopenski S, Aslam A, Zhang X, et al. After chemotherapy treatment for maternal cancer during pregnancy, is breastfeeding possible? Breastfeed Med. 2017;12:91–7. [PubMed: 28170295]
Peccatori FA, Giovannetti E, Pistilli B, et al. "The only thing I know is that I know nothing": 5-fluorouracil in human milk. Ann Oncol. 2012;23:543–4. [PubMed: 22275286]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding



Antimetabolites, Antineoplastic

Antineoplastic Agents

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