Animal studies have failed to reveal evidence of teratogenicity or fetotoxicity; at exposures 30 times (rats) and 2 times (rabbits) the exposure at the maximum recommended human dose of 500 mg twice a day based on body surface area, no teratogenicity or fetotoxicity was observed. No evidence of systemic maternal toxicity observed when administered once daily via oral gavage to pregnant rats at doses up to 3200 mg/kg/day during organogenesis; oral treatment of pregnant rabbits at doses up to 100 mg/kg/day during organogenesis showed minimal maternal toxicity and no external fetal anomalies. There are no controlled data in human pregnancy.

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.

AU TGA pregnancy category: Not formally assigned to a pregnancy category.
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.

See references

Until more data are available, an alternative agent may be preferred, particularly while breastfeeding newborn or preterm infants; caution is recommended.

Excreted into human milk: Yes (active metabolites)

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.

After oral administration, this drug was not found in the bloodstream but was rapidly converted to the active metabolites (tizoxanide and tizoxanide glucuronide) which were detectable in plasma. According to limited data, a maternal dose of 500 mg produced low levels of tizoxanide in breast milk; harmful effects in the nursing infant (especially if older than 2 months) would not be expected.

A lactating mother volunteered to take a single 500 mg oral dose of this drug (as a commercial suspension). The tizoxanide level was 1.4 mg/L at 6 hours after dosing; tizoxanide glucuronide was not measured.

See references