Magnesium sulfate

Eclampsia: stop seizures and prevent recurrence

IV loading + deep IM

Loading once; maintenance every 4 hours

Continue until 24 hours after birth OR the last seizure, whichever is later · Using 50% (500 mg/mL): 4 g = 8 mL; dilute in 100 mL sodium chloride 0.9% and infuse over 15–20 min. Each 5 g IM dose = 10 mL of 50% solution. Check the actual ampoule strength.

Do not give maintenance when toxicity criteria are present; do not run an additional magnesium regimen

Eclampsia: alternative when a reliable infusion pump and monitoring are available

IV infusion

One loading dose, then continuous infusion

24 hours after birth or last seizure, whichever is later · 50% solution: withdraw 8 mL (4 g) into 100 mL sodium chloride 0.9% for loading; for maintenance make 20 g up to a FINAL 100 mL (200 mg/mL), run at 5 mL/hour by labelled pump

• Maintenance concentration and pump rate are calculated from the prescribed 1 g/hour; independently check the preparation.

Use ONE IV or IV/IM protocol; stop/adjust for toxicity or renal dysfunction

Recurrent eclamptic convulsion after loading; reassess airway, glucose and magnesium toxicity

IV infusion

One rescue dose, followed by reassessment

Acute rescue; continue the selected maintenance regimen · 50% solution: 2 g = 4 mL, dilute in compatible sodium chloride 0.9%; give slowly by infusion and check the total loading already received

MSF ceiling: no more than 8 g IV in the first hour; persistent fits need anaesthesia/ICU, not repeated blind magnesium dosing

Imminent preterm birth: NICE offers at 24+0–29+6 weeks and considers at 30+0–33+6 weeks; discuss 23+0–23+6 individually

IV infusion

Loading once, then continuous infusion

Stop at birth or 24 hours, whichever occurs first · 50%: 4 g = 8 mL diluted in compatible sodium chloride 0.9%; maintenance example 20 g made up to FINAL 100 mL, 5 mL/hour via pump

24 hours for neuroprotection; do not add to an eclampsia regimen already running