Background: Endotracheal intubation is often associated with a hypertension and tachycardia. Intravenous MgSO4 is a popular method of blunting this response, because of its ability to depress sympathoadrenal response & catacholamine release. Objective: it was undertaken to compare the effects of 50mg/kg MgSO4 IV given 3 minutes before laryngoscopy and intubation. Methods: A sample size of 60 patients aged 18 to 60 yrs were included in the study and they were allocated into 2 groups of n=30 each. Group I served as control. Group II received 50 mg/ kg of IV magnesium sulphate 3 min before induction. HR, SBP were recorded pre­operatively, 30 sec, 1 min, 3min & 5min after intubation . Results: Patient receiving iv MgSO4 had a better intubating conditions (p<0.04) statistically significant than  in Group I. There was an increase in the HR at 1 minute after intubation compared to basal value (p < 0.01 ). Also, a decrease in SBP observed at 1 minute and 3 min after intubation when compared with basal value (p<0.001) and (p<0.001) respectively. The decrease in RPP at 1 minute & 3 minutte after intubation when compared with the basal value (p <0.001)& (p<0.01) respectively. Conclusion: Magnesium sulphate 50 mg/kg IV infusion 3 minutes before induction, is a simple, effective and practical method of blunting cardiovascular responses to tracheal intubation, not associated with any adverse effect.

Keywords: Laryngoscopy; Tachycardia; Hypertension; Catacholamine.