Isoniazid Pregnancy and Breastfeeding Warnings

Brand names: Nydrazid

Medically reviewed by Drugs.com. Last updated on Oct 6, 2023.

Isoniazid Pregnancy Warnings

This drug should be used during pregnancy only if the benefit outweighs the risk to the fetus.

AU TGA pregnancy category: A
US FDA pregnancy category: C

Comments:
-Some experts recommend using this drug as a treatment for active tuberculosis during pregnancy because the benefit justifies the potential risk to the fetus.
-Preventative therapy should typically be started after delivery.
-Exposed neonates should be monitored for adverse events.

Animal studies have revealed evidence of embryocidal effects with oral administration during pregnancy. There were no teratogenic effects in animal models. There are no controlled data in human pregnancy.

AU TGA pregnancy category A: Drugs which have been taken by a large number of pregnant women and women of childbearing age without any proven increase in the frequency of malformations or other direct or indirect harmful effects on the fetus having been observed.

US FDA pregnancy category C: Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

See references

Isoniazid Breastfeeding Warnings

This drug has been used without apparent harmful effects.

Excreted into human milk: Yes

Comments:
-The US Centers for Disease Control and Prevention (US CDC) and other professional organizations state that breastfeeding should not be discouraged in patients taking this drug.
-The American Academy of Pediatrics considers this drug compatible with breastfeeding.
-The WHO classifies this drug as compatible with breastfeeding; the breastfed infant should be monitored for jaundice.
-Some experts recommend women taking this drug during breastfeeding should take pyridoxine 25 mg orally once a day, and breastfed infants treated with this drug should receive pyridoxine 1 mg/kg orally once a day.
-Drug levels should not be relied upon for prophylaxis or treatment of nursing infants.

In mothers given single oral doses, average peak drug levels in breastmilk occurred at 2 to 3 hours after the dose: 2.1 mg/L (200 mg dose), 5.4 to 5.5 mg/L (300 mg dose), and 9 to 10.6 mg/L (600 mg dose).

The breastfed infants of mothers who took 300 mg once daily for at least 34 days received about 0.3% to 1.2% of the maternal-adjusted dosage of isoniazid.

See references

Further information

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