Is Nalidixic Acid safe while breastfeeding?

Effects on the breastfed infant

Decreased weight gain, pallor, jaundice occurred in a 16-day-old infant probably caused by hemolytic anemia induced by maternal use of nalidixic acid orally 1 gram four times daily and amobarbital 65 mg orally three times daily. The infant developed jaundice, hyperbilirubinemia, reticulocytosis, eosinophilia, Heinz bodies and other signs of hemolysis 7 days after its mother was started on nalidixic acid. No G-6-PD deficiency or hemoglobin Zurich could be demonstrated.[ 1 ]

Effects on milk supply

Relevant published information was not found as of the revision date.

Levels in milk

Maternal Levels. One paper reported old, unpublished data obtained from the manufacturer in which a breastmilk concentration of 2 mg/L was found at an unspecified time in 4 women taking nalidixic acid 1 gram orally 4 times daily.[ 1 ] Thirteen lactating women were given 2 grams of nalidixic acid as a single dose between the third and eighth day postpartum. The average concentration of nalidixic acid in milk during the first four-hour collection period was 0.64 mg/L (range 0.3 to 1.1 mg/L); concentration in milk from other collection periods were as follows: 0.43 mg/L at 4 to 7 hours; 0.2 mg/L at 7 to 10.5 hours; 0.1 mg/L at 10.5 to 16 hours and 0.02 mg/L at 16 to 24 hours after the dose. Using the peak milk level data from this study, the authors estimated that an exclusively breastfed infant would receive a maximum of 300 mcg daily with this maternal dosage regimen, or less than 0.3% of an infant dose.[ 2 ] Infant Levels. Relevant published information was not found as of the revision date.

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