A comparison of intravenous and intramuscular magnesium sulfate regimens in preeclampsia.

A prospective study comparing continuous intravenous magnesium sulfate to intramuscular magnesium sulfate was performed in 32 preeclamptic patients. Eighteen patients received the intramuscular regimen for mild and severe preeclampsia as recommended by Pritchard. The remaining 14 patients received an intravenous regimen consisting of a 4 gm loading dose administered over 15 minutes followed by a maintenance dose of either 1 gm/hr (n = 7) or 2 gm/hr (n = 7). All groups were similar regarding maternal age, height, weight, fetal gestational age, and laboratory findings. The intravenous regimen with a maintenance dose of 1 gm/hr produced serum magnesium levels that were much lower than those achieved with the intramuscular regimen. There was no significant difference after 3 hours of therapy between the mean magnesium levels achieved with the intramuscular regimen and the levels achieved with the intravenous regimen with a maintenance dose of 2 gm/hr. However, during the first 3 hours of therapy the intramuscular regimen for severe preeclampsia produced mean magnesium levels that were significantly higher than those levels obtained with the intravenous regimen with a maintenance dose of 2 gm/hr (p less than 0.001). Both methods were safe. However, the intravenous regimen with a maintenance dose of 1 gm/hr is inadequate in management of preeclamptic patients.