Patients will be allocated into two groups, thirty patients each, Magnesium (M) and Dexmedetomidine (D). Group (M) will receive 40 mg.kg-1 of magnesium sulphate bolus followed by IV infusion of 10 mg.kg-1.h-1. Group (D) will receive dexmedetomidine bolus (1μg.kg-1) followed by infusion of 0.5μg.kg-1h-1 all through the procedure.