Magnesium sulfate dose for preeclampsia?

• A. Magnesium sulfate 4 g in 50 mL NS over 20 min IV/IO
• B. Magnesium sulfate 2 g in 50 mL NS over 10 min IV/IO
• C. Magnesium sulfate 1 g in 50 mL NS over 5 min IV/IO
• D. Magnesium sulfate 3 g in 50 mL NS over 15 min IV/IO

Answer: (B)

Magnesium sulfate is used to prevent seizures in preeclampsia, so the dosing tested here focuses on delivering a loading amount quickly enough to achieve therapeutic levels while staying safe in the field. The best choice gives a moderate loading dose administered via IV over a short, controlled period, using a compatible IV solution (50 mL NS) to reduce the risk of quick, unstable shifts in blood pressure or respiration. This 2 g dose over 10 minutes provides a meaningful starting level without the potential for toxicity that can come with larger or more rapid infusions, and it aligns with EMS protocols that aim for a reliable, in-transit anticonvulsant effect while allowing monitoring.

The other options either underdeliver the dose, which may be ineffective at preventing seizures, or deliver more magnesium too quickly or in a way that isn’t aligned with typical EMS safety margins (for example, smaller, faster boluses or larger doses over shorter times).