FDA Warning: Don’t Use Magnesium Sulfate to Stop Pre-term Labor

The FDA has changed the Pregnancy Category of magnesium sulfate from ‘A’ to ‘D,’ indicating that there is “positive evidence of human fetal risk” when the drug is used during pregnancy. The agency cautions that the drug should not be used for more than 5 to 7 days to stop preterm labor, and using it for longer periods of time could cause hypocalcemia, ostopenia, and fractures in the newborn.

The change comes on the heels of a review of epidemiologic data, along with 18 cases of skeletal abnormalities in newborns exposed to magnesium sulfate. While data shows that lab results in newborns return to normal shortly after birth, the long-term effects on bone health are unknown.

The average length of exposure in newborns with skeletal abnormalities was 10 weeks. Journal Watch’s Allison Bryant wrote that, “There are no data suggesting value to using magnesium sulfate for tocolysis for longer than 48 hours, for neuroprotection beyond when delivery is felt to be imminent, or for seizure prophylaxis in the setting of preeclampsia beyond 24 hours postpartum. Therefore, this FDA warning is unlikely to greatly alter current clinical practice."

Do you agree that this warning is unlikely to change clinical practice? Do you use magnesium sulfate to manage preterm birth?

References:

FDA Drug Safety Communication: FDA Recommends Against Prolonged Use of Magnesium Sulfate to Stop Pre-term Labor Due to Bone Changes in Exposed Babies. May 30, 2013.