In the management of preeclampsia, which route of administration is standard for magnesium sulfate therapy?

• A. Intravenous infusion
• B. Oral tablet
• C. Intramuscular injection
• D. Subcutaneous injection

Answer: (A)

Magnesium sulfate for seizure prevention in preeclampsia must be given in a way that achieves rapid, predictable, and controllable blood levels with close monitoring. Intravenous infusion provides a precise loading dose followed by a maintenance infusion, allowing clinicians to titrate the level and respond quickly if signs of toxicity appear. This is essential in the acute obstetric setting where seizure risk is high and timing matters.

Oral tablets are unreliable for this use because absorption varies widely and onset is slow, which is not acceptable when preventing seizures in preeclampsia. Intramuscular or subcutaneous injections also do not offer reliable absorption or consistent therapeutic levels and can be painful, making them unsuitable for the continuous control needed in this scenario. Therefore, the standard route is intravenous infusion, paired with vigilant monitoring for signs of magnesium toxicity and readiness to administer antidotes if necessary.