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Isoniazid / rifampin Pregnancy and Breastfeeding Warnings

Isoniazid / rifampin is also known as: IsonaRif, Rifamate

Isoniazid / rifampin Pregnancy Warnings

Animal studies have revealed evidence of teratogenicity (including cleft palate and spina bifida) with use of rifampin at doses 0.2 to 2 times the maximum recommended human (MRH) dose. Imperfect osteogenesis and embryotoxicity in animals were also reported at oral rifampin doses about 3 times the MRH dose. Isoniazid may exert an embryocidal effect; however, no isoniazid-related congenital anomalies have been found in animal reproduction studies in mammalian species. There are no controlled data in human pregnancy.

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.

Use is recommended during pregnancy only if the potential benefit outweighs the possible risk to the fetus.

US FDA pregnancy category: C

-When administered during the last few weeks of pregnancy, rifampin can cause postnatal hemorrhages in the mother and infant for which treatment with vitamin K may be indicated.
-Rifampin may affect the reliability of oral or other systemic hormonal contraceptives; advise patients to use alternative birth control methods during treatment.
-Both isoniazid and rifampin have been reported to cross the placental barrier; rifampin has appeared in cord blood.

See references

Isoniazid / rifampin Breastfeeding Warnings

A decision should be made to discontinue breastfeeding or to discontinue this drug, taking into account the importance of this drug to the mother.

Excreted into human milk: Yes

-The Centers for Disease Control and Prevention and other professional organizations state breastfeeding should not be discouraged in women taking rifampin and/or isoniazid.
-Limited data indicates that the low levels of isoniazid and rifampin in breastmilk would not be expected to cause any adverse effects in breastfed infants; however, monitor infants for rare instances of jaundice.
-There is a theoretical risk of convulsions and neuropathy (associated with pyridoxine/Vitamin B6 deficiency) in breastfed infants of mothers taking isoniazid; instruct breastfeeding mothers to administer the one-daily dose of this combination drug before the infant's longest sleep period to decrease the dose the infant receives.
-Advise nursing mothers to concomitantly take 25 mg of oral pyridoxine daily and to give their breastfed infants 1 mg/kg of pyridoxine daily during treatment with this combination drug.

-In mothers given single oral doses of isoniazid, 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).
-After a single 150 mg oral dose of rifampin, drug levels in breastmilk 4 hours after the dose ranged from 0 to 1.8 mL. After a single oral dose of 450 mg, breastmilk levels 12 hours after the dose ranged from 3.4 to 4.9 mg/L.
-The breastfed infants of mothers who took isoniazid 300 mg once daily for at least 34 days received about 0.3% to 1.2% of the maternal-adjusted dosage of isoniazid.
-Normal development was observed in 4 breastfed children (ages 3.9 to 5.1 years) of mothers who received isoniazid and/or rifampin throughout pregnancy and postpartum as part of a multi-drug treatment regimen for tuberculosis; only hyperactivity in 1 child and a mild speech delay in another were noted.

See references

References for pregnancy information

  1. "Product Information. Rifamate (isoniazid-rifampin)." Aventis Pharmaceuticals (2001):
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

References for breastfeeding information

  1. "Product Information. Rifamate (isoniazid-rifampin)." Aventis Pharmaceuticals (2001):
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  3. United States National Library of Medicine "Toxnet. Toxicology Data Network." (2013):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.