Succinylcholine pretreatment with magnesium sulfate.

The effect of pretreatment with 60 mg/kg magnesium sulfate on the neuromuscular blockade and consequent potassium release produced by 1.5 mg/kg succinylcholine in ten normal patients was compared with ten saline pretreated control patients. Magnesium had no significant effect on the characteristics of the paralysis. In control patients, serum potassium increased by an average of 0.57 +/- 0.20 (SEM) mmol/L. No patient in the magnesium group had an increase in serum potassium (mean change -0.05 +/- 0.02 mmol/L). The difference between the groups was statistically significant (P less than 0.01).