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Letermovir Pregnancy and Breastfeeding Warnings

Letermovir is also known as: Prevymis

Medically reviewed on Jan 10, 2018

Letermovir Pregnancy Warnings

Animal studies have revealed evidence of embryofetal developmental toxicity at maternotoxic doses; in rats and rabbits, maternal toxicity was observed with exposures about 11 and 2 times, respectively, the human exposure at the recommended human dose (RHD). In rats, embryofetal developmental toxicity (including skeletal malformations, umbilical cord shortening) and effects due to maternal toxicity (decreased fetal body weight, skeletal variations) were observed at 250 mg/kg/day (about 11 times higher than human exposure at the RHD); no embryofetal toxicities observed at 50 mg/kg/day (about 3 times higher than human exposure at the RHD). In rabbits, developmental toxicities (including spontaneous abortion, increased postimplantation loss, skeletal variations) were observed at a maternally toxic dose of 225 mg/kg/day (about 2 times higher than human exposure at the RHD); no embryofetal toxicities observed at 75 mg/kg/day (less than human exposure at the RHD). There are no controlled data in human pregnancy.

Decreased fertility due to testicular toxicity was observed in male rats; there are no data on the effect of this drug on human fertility.

AU TGA pregnancy category B3: 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 shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.

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: B3
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.

See references

Letermovir Breastfeeding Warnings

The amounts of this drug in breast milk is most likely very low as it is highly bound to plasma proteins.

If the mother requires this drug, it is not a reason to discontinue breastfeeding; however, an alternative agent may be preferred, particularly while breastfeeding newborn or preterm infants.

Excreted into human milk: Unknown
Excreted into animal milk: Yes

Comments:
-No data available on use of this drug during breastfeeding.
-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.

See references

References for pregnancy information

  1. Cerner Multum, Inc. "Australian Product Information." O 0
  2. "Product Information. Prevymis (letermovir)." Merck & Company Inc, Whitehouse Station, NJ.

References for breastfeeding information

  1. Cerner Multum, Inc. "Australian Product Information." O 0
  2. United States National Library of Medicine "Toxnet. Toxicology Data Network. Available from: URL: http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT." ([cited 2013 -]):
  3. "Product Information. Prevymis (letermovir)." Merck & Company Inc, Whitehouse Station, NJ.

Further information

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

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