ORIGINAL CONTRIBUTION activated charcoal whole-bowel irrigation Interaction Between Whole-Bowel Irrigation Solution and Activated Charcoal: Implications for the Treatment of Toxic Ingestions Study objectives: The purpose of this study was to address the issues of safety and efficacy of combining whole-bowel irrigation and activated charcoal administration for the treatment of toxic ingestions. Study design: Two in-vitro studies were performed. In the first, serial ratios of polyethylene glycol (PEG) and activated charcoal (AC) powders were added to water and the solutions were analyzed for PEG concentra- tion and osmolality. In the second, serial ratios of a pharmaceutical bowel irrigation solution and an AC preparation were combined with a constant amount of salicylic acid. Solution osmolalities, PEG, and salicylic acid concentrations were then quantified. Results: Adsorption of PEG powder by AC was demonstrated; however, changes in solution osmolaffty were negligible. Thus, concurrent adminis- tration of these therapies appears safe. However, combining bowel irriga- tion solution with AC resulted in decreased salicylic acid adsorption. This was especially so with smaller amounts of AC that would pertain more to the smaller doses of AC used for multiple-dose charcoal therapy Conclusion: /f these in-vitro data are applicable to overdose patients, the administration of a routine initial charcoal dose to those who will be treated with whole-bowel irrigation would be appropriate. However, it is unlikely that the addition of multiple-dose charcoal therapy to whole- bowel irrigation would provide additional benefit for the patient. [Kirshen- baum LA, Sitar DS, Tenenbein M: Interaction between whole-bowel irriga- tion solution and activated charcoal: Implications for the treatment of toxic ingestions. Ann Emerg Med October 1990;19:1129-1132.] INTRODUCTION Whole-bowel irrigation (WBI) has been proposed as a gastrointestinal de- contamination procedure for treatment of acute overdoses. 1 It is routinely used as a colonoscopy preparative procedure and involves the rapid oral administration of large volumes of commercially available, specialized polyethylene glycol electrolyte lavage solution (PEG-ELS) to irrigate the contents of the gastrointestinal tract. This specific solution was formu- lated to prevent the net absorption or secretion of fluid or electrolytes across the gastrointestinal epithelium, and its safety and effectiveness are reviewed elsewhere, t-,~ Its composition is given (Table 1). Prevention of absorption after the ingestion of ampicillin z and enteric-coated acetylsal- icylic acid 3 has been demonstrated in human beings in controlled volun- teer studies. Effectiveness in iron-overdose patients is supported by a de- scriptive study. 4 Activated charcoal (AC) administration is an accepted therapy for the overdose patient. It is initially administered to prevent the absorption of the ingested toxinS, 6 and then may be given repeatedly to enhance clearance of already absorbed toxins.7, s The purpose of our study was to explore the potential for the concurrent use of these therapies. There is theoretical concern that their combination may not provide increased benefit for the patient and may even produce increased risk. This is because of the presence of PEG as a major constitu- ent of the bowel irrigation fluid. This large molecule (MW, 3,350) could bind to charcoal. If this occurred, the binding sites would be less available for toxin adsorption, thus decreasing the benefit for the patient. Moreover, if significant binding of PEG occurred, the osmolality of the irrigation fluid LA Kirshenbaum, MSc DS Sitar, PhD Mitten Tenenbein, MD Winnipeg, Manitoba, Canada From the Departments of Pharmacology, Medicine, and Pediatrics, University of Manitoba; and the Manitoba Poison Control Centre, Winnipeg, Manitoba, Canada. Received for publication June 16, 1989. Revision received December 11, 1989. Accepted for publication March 15, 1990. Supported in part by the Medical Research Council of Canada. Address for reprints: Milton Tenenbein, MD, Children's Hospital, 840 Sherbrook Street, Winnipeg, Manitoba, Canada R3A 1S1. 19:10 October 1990 Annals of Emergency Medicine 1129/97