[New aspects of anticonvulsive therapy in severe pre-eclampsia and eclampsia]

Parenterally administered magnesium is a reliable and effective treatment to prevent and control convulsions associated with preeclampsia and eclampsia. Because of several side effects in the newborn, especially in the premature child, benzodiazepines are not recommended for prolonged medication. Clomethiazole has also been used with good acceptance, but clinical experience is limited. The anticonvulsive property of magnesium is not clearly understood. Beside a well known peripheral action by neuromuscular blockade through very high serum concentrations, a central mechanism is postulated already at lower levels. The two most widely used regimens of magnesium administration are the intravenous/intramuscular (i.v./i.m.) method popularized by Pritchard and the continuous intravenous (i.v.) route recommended by Zuspan. The concentrations of magnesium in the serum achieved with the i.v./i.m. regimen are significantly higher than those produced by the i.v. administration, especially in the first three hours after initiation of the treatment and if a maintenance dose of 1 g/h is chosen. Although therapeutic concentrations of magnesium effective to prevent seizures have been reported between 1.3 and 4.0 mmol/l, repeated convulsions are occasionally seen during i.v. regimen and at concentrations below 2 mmol/l. Because of this observation, a maintenance dose of 2 g/h and in some cases 3 g/h is required during the first hours of treatment. Side effects in mother and newborn are low, if there is no renal impairment and the treatment instructions are strictly followed. Respiration as well as urinary output have to be monitored at periodic intervals and the patellar reflex should be present. Calcium gluconate, 10 ml of a 10% solution, is an effective antidote in case of magnesium intoxication.