Efficacy and Tolerability of Split-Dose Magnesium Citrate: Low-Volume (2 Liters) Polyethylene Glycol vs. Single- or Split-Dose Polyethylene Glycol Bowel Preparation for Morning Colonoscopy

OBJECTIVES: Preparation regimens for morning colonoscopy are suboptimal. The aim of this study was to test the efficacy and tolerance of a split-dose magnesium citrate-low-volume (2 liters) polyethylene glycol (PEG) regimen for morning colonoscopy. METHODS: A total of 232 patients were randomly assigned to receive 4 liters PEG (day before procedure; group 1, n = 79), 2 liters PEG (day before procedure) followed by another 2 liters PEG (day of procedure; group 2, n = 80), or magnesium citrate (250 ml, day before procedure) followed by 2 liters PEG (day of procedure; group 3, n = 73). The quality of bowel cleansing, tolerability, and adverse effects in group 3 were compared with those in groups 1 and 2. RESULTS: Satisfactory bowel preparation was more frequently reported for group 3 than for group 1 (75% vs. 51%, P = 0.001) and was similar to that for group 2 (75% vs. 76%, P = 0.896). A significantly greater proportion of patients in group 3 graded their overall satisfaction as satisfactory compared with group 1 (43% vs. 23%, P = 0.010), and the proportion was similar to that in group 2 (43% vs. 35%, P = 0.133). Patients in group 3 were more willing to repeat the same preparation regimen, if necessary, than those in group 1 (93% vs. 48%, P < 0.001) or group 2 (93% vs. 62%, P < 0.001). CONCLUSIONS: The split-dose magnesium citrate-low-volume (2 liters) PEG regimen was more efficient than and preferred to the conventional regimen of 4 liters of PEG, and it was equally efficient as, but, again, preferred to the split-dose (2 + 2 liters) regimen for morning colonoscopy.