Magnesium sulfate (MgSO₄) has been used in the treatment of pre-eclampsia, hypertension and arrhythmia. Magnesium enhances the neuromuscular block of rocuronium. This study has been conducted to evaluate the reversal efficacy of sugammadex from deep rocuronium-induced neuromuscular block (NMB) during consistent pretreatment of MgSO₄ in rabbits.

Twenty-eight rabbits were randomly assigned to four groups, a control group or study groups (50% MgSO₄ 150–200 mg/kg and 25 mg/kg/h IV), and received rocuronium 0.6 mg/kg. When post-tetanic count 1–2 appeared, sugammadex 2, 4, and 8 mg/kg was administered in the 2-mg group, control and 4-mg group, and 8-mg group, respectively. The recovery course after reversal of sugammadex administration was evaluated in each group.

The mean serum concentration of magnesium was maintained at more than 2 mmol/L in the study groups, and the total dose of MgSO₄ was more than 590 mg. The reversal effect of sugammadex on rocuronium-induced NMB in pretreated MgSO₄ was not different from that in the group without MgSO₄. The recovery time to train-of-four ratio 0.9 after sugammadex administration in the 2-mg group was longer than in the other groups (P < 0.001); there were no other significant differences among the groups.

The reversal of sugammadex from a deep rocuronium-induced NMB during large pretreatment of MgSO₄ was not affected. However, we should consider that the reversal effect of sugammadex varied depending on the dose.