A randomized, double-blind, placebo-controlled pilot trial of intravenous magnesium sulfate in acute stroke

Magnesium ions act as endogenous vasodilators of the cerebral circulation and act pharmacologically as noncompetitive antagonists of the N-methyl-D-aspartate receptor by virtue of their role as endogenous voltage-sensitive blockers of the ion channel. The preclinical efficacy of magnesium has been demonstrated in standard models of stroke.

Sixty patients were randomized to magnesium sulfate (8 mmol IV over 15 minutes and 65 mmol over 24 hours) or placebo within 12 hours of clinically diagnosed middle cerebral artery stroke. Pulse, blood pressure, and serum magnesium levels were monitored. Primary outcome was death or significant functional impairment (Barthel Index score < 60) at 3 months.

Magnesium was well tolerated, with no significant adverse effects and no change in blood pressure or pulse rate. Laboratory and electrocardiographic variables did not differ significantly between placebo- and magnesium-treated groups. Serum magnesium rose from 0.76 mmol/L to 1.42 mmol/L over 24 hours and remained significantly higher than in the placebo group at 48 hours. Thirty percent of magnesium-treated and 40% of placebo-treated patients were dead or disabled (Barthel Index score < 60) at 3 months (P = .42). There was a decrease in the number of early deaths in the magnesium-treated group (P = .066, log-rank test).

Magnesium sulfate is well tolerated after acute stroke and has no deleterious hemodynamic effects at this dose. Further trials are required to determine efficacy.