Animal studies with IV ceftolozane have failed to reveal evidence of embryofetal toxicity; doses were about 3.5 times higher in mice and 2 times higher in rats than the maximum recommended human dose (MRHD) of 2 g every 8 hours (based on plasma AUC comparison). Animal studies with IV tazobactam have revealed evidence of maternal toxicity but have failed to reveal evidence of fetal toxicity; in rats, maternal toxicity (decreased food intake and body weight gain) was observed at doses about 10 times the MRHD of 1 g every 8 hours (based on body surface area comparison). It is not known if ceftolozane crosses the placenta in animals; tazobactam was shown to cross the placenta in rats and reach levels in the fetus up to 10% of those found in maternal plasma. There are no controlled data in human pregnancy.

AU TGA pregnancy category B1: 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 not shown evidence of an increased occurrence of fetal damage.

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D, and X are being phased out.

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

AU TGA pregnancy category: B1
US FDA pregnancy category: Not assigned.

Risk summary: No data available on use of this drug in pregnant women to inform a drug-related risk.

Comments:
-Available data over several decades have not associated cephalosporin use during pregnancy with major birth defects, miscarriage, or other adverse maternal/fetal outcomes.

See references

LactMed: Use is considered acceptable.
-According to some authorities: The benefit should outweigh the risk to the mother and infant.
-According to some authorities: A decision should be made to discontinue breastfeeding or discontinue the drug, taking into account the importance of the drug to the mother and the benefit of breastfeeding for the infant.

Excreted into human milk: Unknown (ceftolozane, tazobactam)
Excreted into animal milk: Data not available (ceftolozane, tazobactam)

Comments:
-Developmental and health benefits of breastfeeding should be considered as well as the mother's clinical need for this drug.
-The effects in the nursing infant are unknown; potential side effects in the breastfed child due to this drug or the mother's underlying condition should be considered.
-No data available on the clinical use of this drug during breastfeeding; no serious side effects reported for other cephalosporins during breastfeeding.
-Disruption of infant's gastrointestinal flora (resulting in diarrhea or thrush) reported occasionally with cephalosporins; such effects have not been adequately evaluated.

See references