Observations of Dynamic Blood Electrolyte Concentrations After Administration of Colonic Cleansing Lavages

Abstract

Introduction: Colonic cleansing lavages are osmotically active solutions, usually containing salts and/or PEG. To optimize efficacy and safety, the cleansing solution composition should be balanced to promote both adequate fluid volume (to induce a cleansing diarrhea) while also minimizing electrolyte losses or gains from the body. Poorly formulated preparations may provide sufficient cleansing volume but can alter electrolyte concentrations due to diarrheal losses increasing the likelihood of hyponatremia and other hematological abnormalities. A balanced formulation provides sufficient electrolyte supplementation to minimize blood electrolyte excursions. Methods: Healthy men (< 50 yoa) were restricted to a clinic on ad-libitum liquid diet. Cohorts of 5 subjects were given FDA approved bowel preparations: an Oral Sulfate Solution (OSS-SUPREP® Bowel Prep Kit, Braintree Laboratories, Inc.), PEG-ELS (NuLYTELY®, Braintree Laboratories, Inc.) or PEG-EA (MoviPrep® Salix Pharmaceuticals, Inc.), administered according to the manufacturer’s instructions in a split dose regimen. Blood samples were collected for analysis before each dose (pre-dose), and at 1 and 2 hour intervals post dosing. Results: Analysis of blood electrolytes from subjects revealed small fluctuations from baseline in Na, Cl and K post-dosing for all preparations. Small decreases in Na (OSS/PEG-ELS) and Cl (OSS) and increases in Na (PEG-EA), Cl (PEG-EA) and K (OSS/PEG-EA), were determined to be statistically significant (P<0.05) however, in all cases, the mean electrolyte concentration did not deviate outside of the normal ranges for this population. Conclusion: The consumption of osmotically active lavage solutions promotes cleansing by maximizing the fluid volume traversing the colon. However, this process has the potential to alter electrolyte concentrations thereby increasing the possibility of hyponatremia and other hematological imbalances. An investigation of the FDA approved bowel preparations OSS, PEG-ELS and PEG-EA, which were specifically formulated to minimize electrolyte shifts, demonstrates minimal impact on overall blood electrolyte concentration over the duration of the experimental period.510_A Figure 1 No Caption available.510_B Figure 2 No Caption available.510_C Figure 3 No Caption available.