A randomized prospective trial comparing different regimens of oral sodium phosphate and polyethylene glycol-based lavage solution in the preparation of patients for colonoscopy

Background: Regulatory agencies have warned clinicians regarding the risk of electrolyte abnormalities if more than two 45-mL bottles of oral sodium phosphate (NaP) solution are administered within a 24-hour period. Objective: To compare the efficacy, safety, and tolerability of different regimens of oral NaP and polyethylene glycol (PEG). Design: Randomized controlled trial. Setting: Teaching hospital outpatient endoscopy clinic. Patients: Two hundred outpatients without comorbidities who underwent routine colonoscopy. Interventions: Two bottles of NaP 6, 12, or 24 hours apart; or 4 L PEG. Main Outcome Measurements: Bowel preparation quality, patient tolerability, and electrolyte changes. Results: The 12- and 24-hour NaP achieved better cleansing than the 6-hour NaP or PEG. Only 8.5% and 8.3% of patients in the 24- and 12-hour NaP had poor preparations, respectively, compared with 15.6% and 23.4% in the 6-hour NaP and PEG, respectively. The poorer preparation scores with PEG were partly because of a greater amount of colonic fluid. There were no relevant electrolyte changes with PEG, whereas hypokalemia, hypocalcemia, or hyperphosphatemia developed in 5% to 57% of patients on NaP All regimens were poorly tolerated by patients. Limitations: The study was likely underpowered to detect small group differences in electrolytes Conclusions: A 24- or 12-hour NaP bowel preparation strategy was more effective than NaP 6 hours apart or PEG. PEG use is associated with more residual colonic fluid but represents an alternative to NaP in some clinical situations.