Patients were randomly assigned to receive polyethylene glycol ( PEG ) 4000 with simethicon ( PEG-ELS group ) or PEG-4000 with citrates and simethicone plus bisacodyl ( PEG-CS + Bisacodyl group ) , or PEG 3350 with ascorbic acid ( PEG-Asc group ) , or sodium picosulfate plus magnesium oxide and citric acid ( NaPico + MgCit group ) .