Alternative dosing regimen of magnesium sulfate for prevention of eclampsia: An observational prospective study

To evaluate serum magnesium concentrations in pregnant women with severe pre-eclampsia being treated with a novel magnesium sulfate regimen for seizure prevention.

This was a prospective, longitudinal study. Pregnant women aged 18 years or older with severe pre-eclampsia and an indication for treatment with magnesium sulfate were included. Participants received a magnesium sulfate loading dose of 4.5 g over 20 min, then a maintenance dose of 1.5 g/h (the standard regimen at the study center). Serum magnesium concentrations were measured at admission, 30 min, 1, 2, 4, and 6 h, then every 6 h until treatment was stopped. Median (interquartile range [IQR]) serum magnesium concentrations are reported. The primary outcome was serum magnesium concentrations during magnesium sulfate infusion.

Serum magnesium concentrations at admission and after 30 min were 0.77 (IQR 0.72-0.82) and 1.81 (IQR 1.63-1.97) mmol/L, respectively. After 4 h, the concentration had decreased slightly to 1.79 (IQR 1.58-2.02) mmol/L. By 12 h, magnesium levels had stabilized at 2 mmol/L. At this time, 50.9% (28/55) had achieved therapeutic magnesium levels (2.0-3.5 mmol/L), and this proportion had increased to 61.7% (29/47) by 24 h. Magnesium toxicity was observed in three patients (4.7%). No cases of eclampsia or maternal mortality were recorded.

This magnesium sulfate regimen was generally well tolerated and also prevented seizures even though serum magnesium levels at 24 h were below the currently defined therapeutic range in at least one-third of participants.