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Pyrimethamine Pregnancy and Breastfeeding Warnings

Pyrimethamine is also known as: Daraprim

Pyrimethamine Pregnancy Warnings

Pyrimethamine-sulfadoxine was used as part of a study of 357 women in the first or second trimester of pregnancy living in an area of chloroquine-resistant malaria. Pyrimethamine-sulfadoxine treatment (three tablets once) followed by chloroquine prophylaxis was given to 117 women, and pyrimethamine-sulfadoxine treatment followed by a second treatment course at the beginning of the third trimester was given to 136 women. Scleral icterus was observed in five of 177 newborns examined. The most recent dose of pyrimethamine-sulfadoxine administered was 40 to 103 days prior to delivery. There was no other mention of adverse fetal outcome. One woman was treated with pyrimethamine, 25 to 50 mg daily, for central nervous system toxoplasmosis from the twenty-eighth week of gestation until birth. No adverse fetal reactions occurred. Another woman taking weekly chloroquine, dapsone, and pyrimethamine at the time of conception and for 45 days thereafter gave birth to a stillborn infant with a severe defect of the abdominal and thoracic wall and a missing left arm.

Pyrimethamine has been assigned to pregnancy category C by the FDA. Animal studies (at 2.5 to 7 times the normal human dose) have revealed evidence of teratogenicity (cleft palate, brachygnathia, oligodactyly, and microphthalmia). There are no controlled data in human pregnancy. The manufacturer recommends that women should be warned to avoid becoming pregnant during therapy. Pyrimethamine should only be used during pregnancy if the benefit outweighs the risk to the fetus. Because pyrimethamine is a folate antagonist, it should be given with folic acid supplementation if used during pregnancy. For HIV-infected women, the USPHS/IDSA (U.S. Public Health Service/Infectious Diseases Society of America) Prevention of Opportunistic Infections Working Group recommends that chemoprophylaxis be given during pregnancy when necessary to prevent Pneumocystis pneumonia and toxoplasmosis. Sulfamethoxazole-trimethoprim is the drug of choice for this purpose. Pyrimethamine-containing regimens may be considered for prophylaxis against recurrent toxoplasmosis. The Working Group states that primary chemoprophylaxis using pyrimethamine may be deferred until after pregnancy due to the low incidence of toxoplasmic encephalitis during pregnancy and the possible risk associated with pyrimethamine treatment.

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Pyrimethamine Breastfeeding Warnings

Pyrimethamine is excreted into human milk. In three women treated with a combination of dapsone and pyrimethamine, the milk:serum ratio of pyrimethamine ranged from 0.46 to 0.66. The manufacturer reports that after a single 75 mg dose, approximately 3 to 4 mg of the drug is estimated to pass on to the feeding child over 48 hours. The American Academy of Pediatrics considers pyrimethamine to be compatible with breast-feeding. The manufacturer recommends that due to the potential for serious adverse reactions in nursing infants, a decision should be made to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

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References for pregnancy information

  1. Centers for Disease Control and Prevention. "1997 USPHS/IDSA guidelines for the prevention of opportunistic infections in human immunodeficiency virus." MMWR Morb Mortal Wkly Rep 48(RR-12) (1997): 1-46
  2. Hedriana HL, Mitchell JL, Brown GM, Williams SB "Normal fetal outcome in a pregnancy with central nervous system toxoplasmosis and human immunodeficiency virus infection. A case report." J Reprod Med 38 (1993): 747-50
  3. Harpey JP, Darbois Y, Lefebvre G "Teratogenicity of pyrimethamine." Lancet 2 (1983): 399
  4. "Product Information. Daraprim (pyrimethamine)." Glaxo Wellcome, Research Triangle Park, NC.
  5. Schultz LJ, Steketee RW, Macheso A, Kazembe P, Chitsulo L, Wirima JJ "The efficacy of antimalarial regimens containing sulfadoxine-pyrimethamine and/or chloroquine in preventing peripheral and placental plasmodium falciparum infection among pregnant women in malawi." Am J Trop Med Hyg 51 (1994): 515-22

References for breastfeeding information

  1. Clyde DF, et al. "Transfer of pyrimethamine in human milk." J Trop Med HYg 59 (1956): 277-84
  2. "Product Information. Daraprim (pyrimethamine)." Glaxo Wellcome, Research Triangle Park, NC.
  3. "American Academy of Pediatrics. Committee on Drugs. The transfer of drugs and other chemicals into human milk." Pediatrics 108 (2001): 776-89
  4. Edstein MD, et al. "Excretion of chloroquine, dapsone, and pyrimethamine into human milk." Br J Clin Pharmacol 22 (1986): 733-5

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