On arrival to the ERCP suit, two IV cannulae will be inserted in both hands of each patient in both groups. One for isotonic saline infusion and propofol administration and the other will be preserved for the study drug administration. IV fluid will be started at a rate of 8-12 ml.kg-1.h-1 continued throughout the procedure. All patients will be premedicated with intravenous pantoprazole 40mg and ondansetron 8mg.