BackgroundThe pharmacokinetic basis of magnesium sulphate (MgSO 4) dosing regimens for eclampsia prophylaxis and treatment is not clearly established.ObjectivesTo review available data on clinical pharmacokinetic properties of MgSO 4 when used for women with pre‐eclampsia and/or eclampsia.Search strategy MEDLINE, EMBASE, CINAHL, POPLINE, Global Health Library and reference lists of eligible studies.Selection criteriaAll study types investigating pharmacokinetic properties of MgSO 4 in women with pre‐eclampsia and/or eclampsia.Data collection and analysisTwo authors extracted data on basic pharmacokinetic parameters reflecting the different aspects of absorption, bioavailability, distribution and excretion of MgSO 4 according to identified dosing regimens.Main resultsTwenty‐eight studies investigating pharmacokinetic properties of 17 MgSO 4 regimens met our inclusion criteria. Most women (91.5%) in the studies had pre‐eclampsia. Baseline serum magnesium concentrations were consistently <1 mmol/l across studies. Intravenous loading dose between 4 and 6 g was associated with a doubling of this baseline concentration half an hour after injection. Maintenance infusion of 1 g/hour consistently produced concentrations well below 2 mmol/l, whereas maintenance infusion at 2 g/hour and the Pritchard intramuscular regimen had higher but inconsistent probability of producing concentrations between 2 and 3 mmol/l. Volume of distribution of magnesium varied (13.65–49.00 l) but the plasma clearance was fairly similar (4.28–5.00 l/hour) across populations.ConclusionThe profiles of Zuspan and Pritchard regimens indicate that the minimum effective serum magnesium concentration for eclampsia prophylaxis is lower than the generally accepted level. Exposure–response studies to identify effective alternative dosing regimens should target concentrations achievable by these standard regimens.Tweetable abstractMinimum effective serum magnesium concentration for eclampsia prophylaxis is lower than the generally accepted therapeutic level.

ObjectiveTo characterise the current clinical practice patterns regarding the use of magnesium sulphate (MgSO 4) for eclampsia prevention and treatment in a multi‐country network of health facilities and compare with international recommendations.DesignCross‐sectional survey.SettingA total of 147 health facilities in 15 countries across Africa, Latin America and Asia.PopulationHeads of obstetric departments or maternity units.MethodsAnonymous online and paper‐based survey conducted in 2015.Main outcome measuresAvailability and use of MgSO 4; availability of a formal clinical protocol for MgSO 4 administration; and MgSO 4 dosing regimens for eclampsia prevention and treatment.ResultsMagnesium sulphate and a formal protocol for its administration were reported to be always available in 87.4% and 86.4% of all facilities, respectively. MgSO 4 was used for the treatment of mild pre‐eclampsia, severe pre‐eclampsia and eclampsia in 24.3%, 93.5% and 96.4% of all facilities, respectively. Regarding the treatment of severe pre‐eclampsia, 26.4% and 7.0% of all facilities reported using dosing regimens that were consistent with Zuspan and Pritchard regimens, respectively. Across regions, intramuscular maintenance regimens were more commonly used in the African region (45.7%) than in the Latin American (3.0%) and Asian (22.9%) regions, whereas intravenous maintenance regimens were more often used in the Latin American (94.0%) and Asian (60.0%) regions than in the African region (21.7%). Similar patterns were found for the treatment of eclampsia across regions.ConclusionsThe reported clinical use of MgSO 4 for eclampsia prevention and treatment varied widely, and was largely inconsistent with current international recommendations.Tweetable abstractMgSO 4 regimens for eclampsia prevention and treatment in many hospitals are inconsistent with international recommendations.