Pyrimethamine / sulfadoxine Pregnancy and Breastfeeding Warnings

Brand names: Fansidar

Pyrimethamine / sulfadoxine Pregnancy Warnings

Sulfadoxine-pyrimethamine has been assigned to pregnancy category C by the FDA. Sulfadoxine-pyrimethamine has been shown to be teratogenic in rats when given in weekly doses approximately 12 times the normal human dose. Women in endemic areas should be advised to use a reliable form of contraception and avoid becoming pregnant during prophylaxis and for three months after the last dose. Sulfadoxine-pyrimethamine should only be used during pregnancy if the benefit outweighs the risk to the fetus. Because pyrimethamine is a folate antagonist, folic acid supplementation should be given during pregnancy.

Because sulfonamides compete with bilirubin for binding to serum albumin, free bilirubin levels rise in the presence of sulfonamides. Therefore, neonates are at risk of hyperbilirubinemia, jaundice, and kernicterus when sulfonamides are administered to the mother near term (prior to birth, the fetus is able to dispose of bilirubin via the placental circulation).
Sulfadoxine-pyrimethamine prophylaxis is contraindicated at term.

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. No other mention of adverse fetal outcome was made.

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 outcome was reported.

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.

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Pyrimethamine / sulfadoxine 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 American Academy of Pediatrics considers pyrimethamine to be compatible with breast-feeding. Sulfonamides in general are excreted into human milk. For healthy, full-term neonates, sulfonamide excretion into breast milk does not pose a significant risk. Sulfonamides should be avoided if the infant being breast-fed is ill, premature, or has hyperbilirubinemia or glucose-6-phosphate dehydrogenase deficiency. The American Academy of Pediatrics considers some other sulfonamides compatible with breast-feeding of full-term healthy infants. The manufacturer states that sulfadoxine-pyrimethamine therapy is contraindicated during breast-feeding due to the risk of kernicterus from the excretion of sulfonamide into breast milk.

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Further information

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