Magnesium sulfate versus Lidocaine pretreatment for prevention of pain on etomidate injection: A randomized, double-blinded placebo controlled trial

Abstract

Objective: Etomidate is an imidazole derivative and formulated in 35 propylene glycol. When given without a rapid lidocaine injection, etomidate is associated with pain after injection. Magnesium (Mg) is a calcium channel blocker and influences the N-methyl-D-aspartate receptor ion channel. The aim of the study is to evaluate the efficiency of preemptive injection of magnesium sulfate and lidocaine on pain alleviation on etomidate intravenous injection. Methods: In a randomized, double-blinded trial study, 135 adult patients scheduled for elective outpatient or inpatient surgery were divided into three groups. Group M received 620 mg magnesium sulfate, Group L received 3 ml lidocaine 1 and Group S received normal saline, all in a volume of 5 mL followed by a maximal dose of 0.3 mg/kg of 1 etomidate. Pain was assessed on a four-point scale: 0 = no pain, 1 = mild pain, 2 = moderate pain and 3 = severe pain at the time of pretreatment and etomidate injection. Findings: About 60 of patients in the control group had pain during etomidate injection as compared to 22.2 and 40 in the lidocaine and magnesium sulfate groups, respectively. There was difference in induction pain score between three treatment groups, significantly (P = 0.01) and observed differences in pain scores between "normal saline and lidocaine group" (P < 0.001) and "normal saline and magnesium sulfate groups" were statistically meaningful (P = 0.044). Conclusion: Intravenous magnesium sulfate and lidocaine injection are comparably effective in reducing etomidate-induced pain.