The Basics
What is Pyrimethamine?
Used as an antimalarial or with a sulfonamide to treat toxoplasmosis.
Brand names for Pyrimethamine
Daraprim
How Pyrimethamine is classified
Anti-infective Agents, Antiparasitic Agents, Antimalarials, Antiprotozoal Agents
Pyrimethamine During Pregnancy
Pyrimethamine pregnancy category
Category CNote that the FDA has deprecated the use of pregnancy categories, so for some medications, this information isn’t available. We still think it’s useful to list historical info, however, given what a common proxy this has been in the past.
What we know about taking Pyrimethamine while pregnant
Pyrimethamine has been shown to be teratogenic in rats when given in oral doses 7 times the human dose for chemoprophylaxis of malaria or 2.5 times the human dose for treatment of toxoplasmosis. At these doses in rats, there was a significant increase in abnormalities such as cleft palate, brachygnathia, oligodactyly, and microphthalmia. Pyrimethamine has also been shown to produce terata such as meningocele in hamsters and cleft palate in miniature pigs when given in oral doses 170 and 5 times the human dose, respectively, for chemoprophylaxis of malaria or for treatment of toxoplasmosis. There are no adequate and well-controlled studies in pregnant women. DARAPRIM should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Concurrent administration of folinic acid is strongly recommended when used for the treatment of toxoplasmosis during pregnancy.
Taking Pyrimethamine While Breastfeeding
What are recommendations for lactation if you're taking Pyrimethamine?
No adverse reactions in breastfed infants have been reported and it is acceptable in nursing mothers. In HIV-infected women, elevated viral HIV loads in milk were decreased after treatment with chloroquine to a greater extent than other women who were treated with the combination of sulfadoxine and pyrimethamine.[1] It has been suggested that maternal pyrimethamine clearance might be increased during lactation, but data are insufficient to make a definitive conclusion.[2][3]
Maternal / infant drug levels
No adverse reactions in breastfed infants have been reported and it is acceptable in nursing mothers. In HIV-infected women, elevated viral HIV loads in milk were decreased after treatment with chloroquine to a greater extent than other women who were treated with the combination of sulfadoxine and pyrimethamine.[1] It has been suggested that maternal pyrimethamine clearance might be increased during lactation, but data are insufficient to make a definitive conclusion.[2][3]
Possible effects of Pyrimethamine on milk supply
Relevant published information was not found as of the revision date.
Possible alternatives to Pyrimethamine
List of References
Lactation sources: Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK501922/1. Semrau K, Kuhn L, Kasonde P et al. Impact of chloroquine on viral load in breast milk. Trop Med Int Health. 2006;11:800-3. PMID: 16772000
2. Salman S, Davis TME. Regarding Lactation Status and Studies of Pyrimethamine Pharmacokinetics in Pregnancy . CPT Pharmacometrics Syst Pharmacol. 2017;6:730. PMID: 29064165
3. de Kock M, Tarning J, Barnes KI, Denti P. Response to Lactation Status and Studies of Pyrimethamine Pharmacokinetics in Pregnancy . CPT Pharmacometrics Syst Pharmacol. 2017;6:731. PMID: 29052341
4. Clyde DF. An examination of factors involved in the transfer of pyrimethamine in human milk. East Afr Med J. 1957;34:81-5. PMID: 13437933
5. Clyde DF, Press J, Shute GT. Transfer of pyrimethamine in human milk. J Trop Med Hyg. 1956;59:277-84. PMID: 13385913
6. Edstein MD, Veenendaal JR, Newman K et al. Excretion of chloroquine, dapsone and pyrimethamine in human milk. Br J Clin Pharmacol. 1986;22:733-5. PMID: 3567020
7. Clyde DF. Prolonged malaria prophylaxis through pyrimethamine in mothers’ milk. East Afr Med J. 1960;37:659-60. PMID: 13694157
Disclaimer: This material is provided for educational purposes only and is not intended for medical advice, diagnosis, or treatment. Consult your healthcare provider with any questions.
