Methylnaltrexone Pregnancy and Breastfeeding Warnings

Brand names: Relistor

Medically reviewed by Drugs.com. Last updated on Jan 19, 2024.

Methylnaltrexone Pregnancy Warnings

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

AU TGA pregnancy category: B1
US FDA pregnancy category: C

May precipitate opioid withdrawal in a fetus

Animal studies have revealed evidence of reproductive toxicity at high doses; however no evidence of teratogenicity has been reported in rats or rabbits. Use of this drug during pregnancy may precipitate opioid withdrawal in a fetus due to the immature fetal blood brain barrier. 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 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.

See references

Methylnaltrexone Breastfeeding Warnings

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: Unknown
Excreted into animal milk: Yes

The effects in the nursing infant are unknown.

See references

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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