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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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Last Revision: January 7, 2019.

Estimated reading time: 1 minute

CASRN: 41708-72-9

Chemical structure

Drug Levels and Effects

Summary of Use during Lactation

Tocainide was removed from the market in the United States in 2003 because it can cause serious and potentially fatal hematological adverse effects. Limited data indicate that rather large amounts of tocainide are excreted into breastmilk. Because of the relative lack of data concerning breastfeeding during maternal tocainide therapy and is potential toxicity, tocainide should be avoided during breastfeeding.

Drug Levels

Maternal Levels. One woman taking tocainide 400 mg every 8 hours orally during the early postpartum period had levels of 12 mg/L at 0.5 hour before a dose and 28 mg/L at 2 hours after a dose.[1] These data indicate that an exclusively breastfed infant would receive between 9 and 21% of the maternal weight-adjusted dosage.

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.


Wilson JH. Breast milk tocainide levels. J Cardiovasc Pharmacol. 1988;12:497. Letter. [PubMed: 2465453]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

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.

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

Bookshelf ID: NBK501117PMID: 30000176


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