Background: Colonoscopy is one of the most commonly performed outpatient procedures 
throughout the world as a screening, diagnostic, and therapeutic tool. propofol is the most 
common drug used for sedation during endoscopy either alone or in combination with another 
agent. Patients and Methods: A total of 90 patients of both gender aged between 18 and 70 
years with American Society of Anesthesiologists grade I and II patients scheduled to 
undergo colonoscopy, under sedation were included in the study. Patients were randomly 
allocated into 3 equal groups each containing 30 patient. Group (L) received 1.5 mg/ kg of 
lidocaine IV before induction by propofol and continuous infusion of lidocaine 4 mg kg/ h 
after induction, group (M) received50 mg/ kg of magnesium sulphate before induction by 
propofol and continuous infusion of magnesium 8 mg/ kg/h after induction and group (O) as 
control group received normal saline 0.9% Sodium Chloride. Results: There was a significant 
difference in intraoperative hemodynamic stability, total amount of propofol, post procedural 
pain and analgesic demand, and patient between three groups. Conclusion: we concluded that 
lidocaine infusion by dose 1.5 mg/kg loading and 4 mg/kg/ h as maintenance is more effective 
than magnesium sulfate by dose 50 mg/kg loading and 8 mg/kg/ h maintenance in decreasing 
total amount of propofol, post procedural pain and analgesic demand, and improving patient 
satisfaction in patient undergoing colonoscopy under sedation with propofol.