Linezolid Pregnancy and Breastfeeding Warnings

Brand names: Zyvox

Medically reviewed by Drugs.com. Last updated on Jun 5, 2023.

Linezolid Pregnancy Warnings

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

AU TGA pregnancy category: B3
US FDA pregnancy category: C

Animal studies have failed to reveal evidence of teratogenicity, but embryofetal toxicity was observed at maternotoxic doses. Embryofetal toxicity included increased postimplantation embryolethality (including total litter loss), decreased fetal weights, and increased rate of costal cartilage fusion in mice with maternal toxicity (clinical signs, reduced weight gain); decreased fetal weights, reduced sternebrae ossification, decreased pup survival, and mildly delayed maturation in rats with slight maternal toxicity (reduced weight gain); and reduced fetal weights in rabbits with maternal toxicity (clinical signs, reduced weight gain, reduced food intake). Placental transfer of this drug and/or its metabolites was observed in rats. There are no controlled data in human pregnancy.

AU TGA pregnancy category B3: Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.

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.

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Linezolid Breastfeeding Warnings

LactMed: Use of this drug is not a reason to discontinue breastfeeding if it is required by the mother; alternate therapy may be preferred, especially if the nursing infant is premature or younger than 1 month.
-According to some authorities, breastfeeding is not recommended during use of this drug and should be discontinued before starting therapy.
-According to other authorities, caution is recommended.

Excreted into human milk: Yes

Comments:
-The effects in the nursing infant are unknown; according to some experts, the nursing infant should be monitored for possible effects on the gastrointestinal tract (e.g., diarrhea, vomiting, candidiasis [thrush, diaper rash]).

Drug levels in breast milk are likely effective against staphylococcal strains found in mastitis. Based on limited data, the maximum dose an infant would receive via breast milk would be much less than the usual infant dose (maximum infant dose: 30 mg/kg/day).

Milk samples were collected at 10 time points over 24 hours from a 32-year-old lactating woman after a single 600 mg oral dose. The peak breast milk drug level (12.4 mg/L) was reached 2 hours after dosing. Milk levels decreased with a half-life of 6.5 hours and were detectable up to 24 hours after dosing. Based on this data, an exclusively breastfed infant would receive about 2 mg/kg/day (estimated maximum) from the maximum recommended maternal dose.

A woman was treated with 600 mg orally every 12 hours for methicillin-resistant Staphylococcus aureus mastitis. Milk was pumped from both breasts 8 times daily on the 1st and 14th day of therapy. Peak breast milk drug levels averaged 9.75 and 18.73 mg/L on day 1 and 14, respectively. According to author calculation, a fully breastfed infant would receive 7.85% and 15.61% of the weight-adjusted maternal dose on day 1 and 14, respectively. Based on the milk level on day 14, a fully breastfed infant would receive 1.84 mg/kg/day.

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Further information

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