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

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

Risk summary: Insufficient data available on use of this drug in pregnant women to inform a drug-related risk.

Animal studies have failed to reveal evidence of fetal harm. 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.

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In a case study, a nursing mother received 500 mg (6.7 mg/kg) IV once a day for 28 days. Samples of breast milk were collected over a 24-hour period (six 4-hour intervals) on day 27. The highest drug level measured in breast milk was 44.7 ng/mL (in the second sample). The 5th sample (ended 20 hours after dosing) contained 29.2 ng/mL; the final sample had no detectable drug (less than 25 ng/mL). The calculated maximum daily dose to the infant (assuming mean milk consumption of 150 mL/kg/day) was 0.1% of the maternal dose. No side effects were observed in the nursing infant during the 28 days of maternal therapy or at follow-up.

A nursing woman received 500 mg (7.4 mg/kg) IV once a day for 14 days. Hindmilk samples were collected during the last 4 days of therapy and for 2 days after the last dose. Trough drug levels measured during therapy averaged 208 mcg/L; at 6 and 12 hours after 1 of the doses, levels of about 270 mcg/L were observed. After the last dose, milk levels decreased from 330 mcg/L to 121 mcg/L over 42 hours. Using the median milk level, the infant would receive a weight-adjusted dose of 0.5% of the maternal dose. No side effects were observed in the nursing infant during maternal therapy or for 7 days after the last maternal dose.

LactMed: No special precautions needed.
-According to some authorities: Breastfeeding is not recommended during use of this drug.

Excreted into human milk: Yes (low levels)

Comments:
-Developmental and health benefits of breastfeeding should be considered as well as the mother's clinical need for this drug.
-Due to the large molecular weight of this drug (1620.67 daltons) and high protein binding (90% to 93%), amount of drug exposure for a nursing infant appears very low; poor oral bioavailability further reduces systemic exposure for the nursing infant.
-This drug is not expected to harm a nursing infant; potential side effects in the breastfed child due to this drug or the mother's underlying condition should be considered.

See references