FDA Drug Safety Podcast: FDA Recommends Against Prolonged Use of Magnesium Sulfate to Stop Pre-term Labor Due to Bone Changes in Exposed Babies

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Narrator: Welcome to the FDA Drug Safety Podcast from the Division of Drug Information. Today’s topic: FDA recommends against prolonged use of magnesium sulfate to stop pre-term labor due to bone changes in exposed babies.

CDR Ray Ford, a U.S. Public Health Service pharmacist in the Division, will provide you with additional information about this communication.

CDR Ray Ford: On May 30, 2013 the FDA advised health care professionals against using magnesium sulfate injection for more than 5 to 7 days to stop pre-term labor in pregnant women.  This use of the drug is off-label, which means that it is not an FDA-approved use of the drug. Administration of magnesium sulfate injection to pregnant women longer than 5 to 7 days may lead to low calcium levels and bone problems in the developing baby or fetus, including thin bones, called osteopenia, and bone breaks, called fractures.  The shortest duration of treatment that can result in harm to the baby is not known. 

Magnesium sulfate is approved to prevent seizures in preeclampsia, a condition in which the pregnant woman develops high blood pressure and protein in the urine, and for control of seizures in eclampsia.  Both preeclampsia and eclampsia are life-threatening complications that can occur during pregnancy.  Preeclampsia can lead to eclampsia, seizures, stroke, multiple organ failure, and death of the woman and/or baby.

In light of this new safety information about low calcium levels and bone problems in the developing baby, the following information is being added to the drug label for Magnesium Sulfate Injection, USP 50%:

  • A new Warning stating that continuous administration of magnesium sulfate injection beyond 5 to 7 days in pregnancy for the treatment of pre-term labor can cause low calcium levels and bone changes in the baby.
  • A new Labor and Delivery section emphasizing that continuous administration of magnesium sulfate injection to treat pre-term labor is not approved and that the safety and efficacy of use for this indication are not established. 
  • A new Teratogenic Effects section conveying the potential harm to the developing babies by changing the Pregnancy Category to D from A. This section also includes the concerns described under the new Warning. It should be noted that “Pregnancy Category D” means there is positive evidence of human fetal risk, but the potential benefits from using the drug in pregnant women may be acceptable in certain situations despite its risks. “Pregnancy Category A” means that adequate and well-controlled studies have failed to demonstrate a risk to the fetus in the first trimester of pregnancy, and there is no evidence of risk in later trimesters.

The manufacturers of other magnesium sulfate injection products have made similar changes to their drug labels.

At this time FDA recommends Healthcare Professionals be mindful of the following:

  • Administration of magnesium sulfate injection beyond 5 to 7 days to treat pregnant women can cause low calcium and bone abnormalities in the fetus.  The shortest duration of treatment that can result in fetal harm is not known.
  • Magnesium sulfate injection should only be used during pregnancy if clearly needed.  If the drug is used during pregnancy, the health care professional should inform the patient of the potential harm to the fetus.
  • When used in pregnant women for conditions other than its approved indication, magnesium sulfate injection should be administered only by trained obstetrical personnel in a hospital setting with appropriate obstetrical care facilities.
  • Report adverse events involving magnesium sulfate to the FDA MedWatch program at www.fda.gov/medwatch.  

Narrator: Thank you for listening. The FDA is committed to keeping healthcare professionals informed of the latest safety information.  A link to this communication and the complete data summary can be found at www.fda.gov/DrugSafetyCommunications. If you have drug questions, you can reach us at druginfo@fda.hhs.gov.

Prescribers...be sure that your patients are filling their mail-order prescriptions at legitimate online US pharmacies by guiding them to the BeSafeRx online pharmacy map and other resources on FDA’s website.

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Page Last Updated: 10/20/2015
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