The MAGPIE trial (2002) established magnesium sulfate as the standard anticonvulsant in pre-eclampsia. The primary mechanism by which magnesium sulfate prevents seizures in eclampsia is:

• A Blockade of NMDA glutamate receptors and cerebrovascular vasodilation ✓
• B Enhancement of GABA-A receptor activity in the cerebral cortex
• C Direct sodium channel blockade in cortical neurons
• D Inhibition of prostaglandin synthesis in the blood-brain barrier

Explanation

Magnesium sulfate acts primarily as an NMDA receptor antagonist, blocking the excitatory effects of glutamate; it also promotes cerebrovascular vasodilation by reducing cerebral vasospasm and may block calcium entry into neurons. This dual mechanism—reducing excitatory neurotransmission and improving cerebral perfusion—underlies seizure prevention. GABA enhancement is the mechanism of benzodiazepines, not magnesium. The MAGPIE trial showed a 58% relative risk reduction in eclampsia with MgSO4 over placebo.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.