Ideal Magnesium Sulfate Dose ID'd for Fetal Neuroprotection

Individual maternal serum magnesium levels were simulated at the time of delivery for each woman
Individual maternal serum magnesium levels were simulated at the time of delivery for each woman

A new study has identified a therapeutic target serum level for magnesium sulfate in order to optimize and prevent cerebral palsy in preterm infants.

Magnesium sulfate is indicated for fetal neuroprotection in pre-32 week gestation deliveries. Researchers from Stanford University, Oregon Health and Science University and Beni-Suef University (Egypt) applied an existing pharmacokinetic model to the cohort in the BEAM (Beneficial Effects of Antenatal Magnesium Sulfate) study, which evaluated the neuroprotection of magnesium sulfate in 20 different centers across the U.S. between December 1997 and May 2004.

A total of 636 women were administered magnesium sulfate and 1,269 received a placebo. The researchers simulated the individual maternal serum magnesium levels at the time of delivery for each woman in the cohort by using the time of the last magnesium sulfate administration relative to time of birth and the duration of administration. 

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Twenty-three infants had cerebral palsy: 3.6% in the magnesium sulfate group and 6.4% in the control group. The analysis found that the simulated maternal serum concentration associated with the lowest probability of infant cerebral palsy was 4.1mg/dL (95% CI: 3.7 to 4.4), while the simulated total administered magnesium dose associated with the lowest probability of delivering an infant with cerebral palsy was 64g (95% CI: 30 to 98). The probability of delivering a baby without cerebral palsy with these simulated optimized doses was 98% and 96%, respectively.

“This study is the first to use pharmacokinetic modeling to suggest a therapeutic target maternal serum level we should aim for," said Dr. Kathleen Brookfield, lead author of study. “The dose of magnesium sulfate can now be tailored depending on maternal factors and the clinical situation to achieve this target.”

Researchers concluded that their results suggest consideration be given to “modifying current magnesium sulfate dosing regimens to help achieve adequate magnesium exposure prior to delivery to optimize fetal neuroprotection and minimize the risk of cerebral palsy.”

For more information visit wiley.com.