Magnesium sulphate for prevention of eclampsia: are intramuscular and intravenous regimens equivalent? A population pharmacokinetic study
Article first published online: 26 MAR 2013
© 2013 The Authors BJOG An International Journal of Obstetrics and Gynaecology © 2013 RCOG
BJOG: An International Journal of Obstetrics & Gynaecology
Volume 120, Issue 7, pages 894–900, June 2013
How to Cite
Magnesium sulphate for prevention of eclampsia: are intramuscular and intravenous regimens equivalent? A population pharmacokinetic study. BJOG 2013;120:894–900., , , , , , .
- Issue published online: 10 MAY 2013
- Article first published online: 26 MAR 2013
- Manuscript Accepted: 18 FEB 2013
- Macarthur Foundation
- Magnesium sulphate;
To compare magnesium sulphate concentrations achieved by intramuscular and intravenous regimens used for the prevention of eclampsia.
Low-resource obstetric hospitals in Nagpur and Vellore, India.
Pregnant women at risk for eclampsia due to hypertensive disease.
A pharmacokinetic study was performed as part of a randomised trial that enrolled 300 women comparing intramuscular and intravenous maintenance regimens of magnesium dosing. Data from 258 enrolled women were analysed in the pharmacokinetic study. A single sample was drawn per woman with the expectation of using samples in a pooled data analysis.
Main outcome measures
Pharmacokinetic parameters of magnesium distribution and clearance.
Magnesium clearance was estimated to be 48.1 dl/hour, volume of distribution to be 156 dl and intramuscular bioavailability to be 86.2%. The intramuscular regimen produced higher initial serum concentrations, consistent with a substantially larger loading dose. At steady state, magnesium concentrations in the intramuscular and intravenous groups were comparable. With either regimen, a substantial number of women would be expected to have serum concentrations lower than those generally held to be therapeutic.
Clinical implications were that a larger loading dose for the intravenous regimen should be considered; where feasible, individualised dosing of magnesium sulphate would reduce the variability in serum concentrations and might result in more women with clinically effective magnesium concentrations; and lower dose magnesium suphate regimens should be considered with caution.