title: 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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  Intravenous magnesium sulfate and lidocaine injection are comparably effective in reducing etomidate-induced pain.
authors.affiliation: Anesthesiology and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Mohammadreza
authors.initials: M
authors.lastname: Safavi
authors.affiliation: Anesthesiology and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Azim
authors.initials: A
authors.lastname: Honarmand
authors.affiliation: Anesthesiology and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Ashraf Sadat
authors.initials: AS
authors.lastname: Sahaf
authors.affiliation: Anesthesiology and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Seyyed Mohammad
authors.initials: SM
authors.lastname: Sahaf
authors.affiliation: Anesthesiology and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Mohammadali
authors.initials: M
authors.lastname: Attari
authors.affiliation: Anesthesiology and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Mahsa
authors.initials: M
authors.lastname: Payandeh
authors.affiliation: Anesthesiology and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Iazdani
authors.affiliation: Anesthesiology and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Nilofarsaddat
authors.initials: N
authors.lastname: Norian
keywords: Etomidate; Lidocaine; Magnesium sulfate; pain; pretreatment; prevention