In preeclampsia/eclampsia management, what is the role of magnesium sulfate?

• A. Magnesium sulfate is used for seizure prophylaxis.
• B. Magnesium sulfate is used to lower blood pressure directly.
• C. Magnesium sulfate is contraindicated.
• D. Magnesium sulfate cures preeclampsia.

Answer: (A)

Magnesium sulfate acts as an anticonvulsant in preeclampsia and eclampsia. It is used to prevent seizures in women with preeclampsia and to treat active seizures if they occur (eclampsia). It works by reducing neuronal excitability in the CNS, likely through NMDA receptor antagonism and calcium channel effects, which helps prevent the brain from undergoing seizures.

This is not a direct blood pressure medication, and magnesium sulfate does not cure preeclampsia. Blood pressure control and definitive management (often delivery) address the underlying disease, while magnesium sulfate specifically lowers the risk of seizures.

Therapy is typically started with a loading dose followed by continuous infusion and is continued for a period after the risk of seizures subsides (such as 24 hours after the last seizure or postpartum, per protocol). Monitoring is essential for toxicity: reduced deep tendon reflexes, respiratory depression, and decreased urine output can signal toxicity, in which case the infusion is stopped and calcium gluconate is given as an antidote.