Indication
Eclampsia, torsades, severe asthma, hypomagnesaemia.
Preparation
Eclampsia: 4 g in 100 mL NS over 20 min, then 1 g/h infusion.
Dilution
20 g in 500 mL NS (40 mg/mL) for infusion.
Rate
Eclampsia 1–2 g/h. Torsades 2 g IV over 10 min. Asthma 2 g over 20 min.
Monitoring
- • Patellar reflexes
- • RR (hold if <12)
- • Urine output
- • Mg level (target 4–7 mEq/L in eclampsia)
Common errors
- • Overdose → respiratory depression — treat with 1 g Ca gluconate IV
Pearls
- • Loss of patellar reflex is first sign of toxicity
