This drug should be used during pregnancy only if clearly needed.

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

Animal studies have failed to reveal evidence of fetolethality. There are no controlled data in human pregnancy; however, this drug has been used in various stages of human pregnancy without evidence of fetal harm. No adverse effects related to pregnancy were observed in 345 obstetrical patients using this drug.

This drug crosses the placenta and can achieve cord serum levels about 25% that of the mother. After multiple 600 mg IM injections, there was no significant accumulation in the amniotic fluid. No effects on the newborn were observed.

The children of 302 patients treated with 2 g orally per day for 7 days at different stages of pregnancy were evaluated at various intervals up to 7 years after birth. No increases in malformations or delayed development were observed, when compared with a control group.

The injectable solution contains benzyl alcohol, which can cross the placenta.

AU TGA pregnancy category A: Drugs which have been taken by a large number of pregnant women and women of childbearing age without any proven increase in the frequency of malformations or other direct or indirect harmful effects on the fetus having been observed.

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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Drug levels of 0.5 to 2.4 mcg/mL have been reported in human breast milk. In 1 study, serum and milk levels measured 6 hours postdose in 9 patients administered 500 mg orally every 6 hours for 3 days averaged 1.37 and 1.28 mcg/mL, respectively, representing a milk to plasma ratio of 0.9. Much lower milk to plasma ratios of 0.13 to 0.17 have also been reported. No adverse effects have been reported in nursing infants.

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

Excreted into human milk: Yes

Comments: The effects in the nursing infant are unknown.

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