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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: March 17, 2021.

Estimated reading time: 2 minutes

CASRN: 55268-74-1

image 135002924 in the ncbi pubchem database

Drug Levels and Effects

Summary of Use during Lactation

Because of the minute levels of praziquantel in breastmilk, amounts ingested by the infant are small and would not be expected to cause any adverse effects in breastfed infants. Expert opinion holds that lactation should not be a contraindication to maternal treatment with praziquantel.[1-3] To minimize infant exposure, a single dose can be taken just before the infant's longest sleep period or an alternate method of feeding (e.g., stored milk) can be used for 24 hours after a single dose or the last of a series of doses.[4]

Drug Levels

Maternal Levels. Five women were given a single oral dose of praziquantel of about 50 mg/kg. The average peak milk level of 440 mcg/L usually occurred 2 hours after the dose, although the peak occurred 6 hours after the dose in 1 individual. By 24 hours after the dose, the drug was undetectable (<4 mcg/L) in 4 women and near the lower limit of detection (6 mcg/L) in the other. The authors calculated that the average amount excreted into milk in 24 hours was 27 mcg (range 6.8 to 75 mcg) which corresponded to 0.0087% of the total (not weight-adjusted) dosage.[5]

The same paper reported another 5 women given three 20 mg/kg oral doses at 4-hour intervals. With this regimen, peaks were observed 4 and 10 hours after the first dose. A meal near the second dose probably delayed its absorption. The peaks were 250 and 460 mcg/L, respectively. The authors calculated that the average amount excreted into milk in 24 hours was 25.6 mcg (range 4.6 to 49 mcg) which corresponded to 0.0007% of the total (not weight-adjusted) dosage.[5]

Fifteen women in the Philippines who were 5 to 7 months postpartum and infected with Schistosoma japonicum were given praziquantel 30 mg/kg twice at an interval of 3 hours. The average milk praziquantel level was 0.185 mg/L. Praziquantel elimination from milk had a half-life averaging 1.9 hours and paralleled plasma elimination. By 24 hours after the dose, the milk level was estimated to be 4 mcg/L. Using the average milk level, the authors estimated that a fully breasted infant would receive about 0.028 mg/kg daily, which would be about 0.05% of the maternal weight-adjusted dosage.[6]

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.


Allen HE, Crompton DW, de Silva N, et al. New policies for using anthelmintics in high risk groups. Trends Parasitol. 2002;18:381–2. [PubMed: 12377247]
Olds GR. Administration of praziquantel to pregnant and lactating women. Acta Tropica. 2003;86:185–95. [PubMed: 12745136]
Friedman JF, Olveda RM, Mirochnick MH, et al. Praziquantel for the treatment of schistosomiasis during human pregnancy. Bull World Health Organ. 2018;96:59–65. [PMC free article: PMC5791873] [PubMed: 29403101]
Porto I. Antiparasitic drugs and lactation: Focus on anthelmintics, scabicides, and pediculicides. J Hum Lact. 2003;19:421–5. [PubMed: 14620457]
Pütter J, Held F. Quantitative studies on the occurrence of praziquantel in milk and plasma of lactating women. Eur J Drug Metab Pharmacokinet. 1979;4:193–8. [PubMed: 575330]
Bustinduy AL, Kolamunnage-Dona R, Mirochnick MH, et al. Population pharmacokinetics of praziquantel in pregnant and lactating Filipino women infected with Schistosoma japonicum. Antimicrob Agents Chemother. 2020;64:e00566–20. [PMC free article: PMC7449211] [PubMed: 32631820]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding


Anti-Infective Agents


Antiparasitic Agents

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: NBK501384PMID: 30000443


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