Document Type : Original Article

Authors

• . Mohammadreza Safavi
• . Azim Honarmand
• . Ashraf Sadat Sahaf
• . Seyyed Mohammad Sahaf
• . Mohammadali Attari
• . Mahsa Payandeh
• . Alireza Iazdani
• . Nilofarsaddat Norian

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.

Keywords

• Etomidate
• Lidocaine
• Magnesium sulfate
• pain
• pretreatment
• prevention