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Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006-.

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Drugs and Lactation Database (LactMed®) [Internet].

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Methylnaltrexone

Last Revision: December 15, 2023.

Estimated reading time: 1 minute

CASRN: 83387-25-1

image 391042346 in the ncbi pubchem database

Drug Levels and Effects

Summary of Use during Lactation

No information is available on the use of methylnaltrexone during breastfeeding. The manufacturer recommends avoiding breastfeeding in mothers taking methylnaltrexone. Based on pharmacokinetic data, the oral absorption of methylnaltrexone appears to be very low. Observe breastfed infants who have been exposed to opioids during pregnancy or postpartum for signs of opioid withdrawal, especially diarrhea.

Drug Levels

Based on the serum AUC values of oral and subcutaneous methylnaltrexone in the product labeling, it appears that methylnaltrexone has an oral bioavailability of <5%.

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

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.

Substance Identification

Substance Name

Methylnaltrexone

CAS Registry Number

83387-25-1

Drug Class

Breast Feeding

Lactation

Milk, Human

Narcotic Antagonists

Disclaimer: Information presented in this database is not meant as a substitute for professional judgment. You should consult your healthcare provider for breastfeeding advice related to your particular situation. The U.S. government does not warrant or assume any liability or responsibility for the accuracy or completeness of the information on this Site.

Copyright Notice

Attribution Statement: LactMed is a registered trademark of the U.S. Department of Health and Human Services.

Bookshelf ID: NBK564288PMID: 33226751

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