In adult eclampsia with seizures, what is the initial magnesium sulfate dose?

• A. 4 gm IV/IO slow IV push over three to four minutes
• B. 2 gm IV/IO bolus over five minutes
• C. 6 gm IV push over 2 minutes
• D. 4 gm IM over 5 minutes

Answer: (A)

The key idea is rapidly achieving therapeutic magnesium levels to prevent and control seizures in adult eclampsia. The standard loading dose is 4 g given IV or IO over about 3–4 minutes. IV administration provides the quickest and most reliable rise in serum magnesium, which is crucial during an active seizure. A slow IV push helps minimize side effects while still reaching therapeutic levels promptly.

Other approaches are less appropriate in this emergent setting. A smaller dose may not reach anticonvulsant levels quickly enough to stop ongoing seizures. A larger IV push over a very short time increases the risk of toxicity, including respiratory depression and hypotension. Intramuscular dosing can be slower and with more variable absorption, making it less reliable when rapid control of seizures is needed.

After the loading dose, a maintenance infusion (typically 1–2 g/hour) is used to maintain therapeutic levels as you monitor the patient.