Irrigation is indicated for any of the following: Some serious poisonings due to sustained-release preparations or substances that are not adsorbed by charcoal (eg, heavy metals) Drug packets (eg, latex-coated packets of heroin or cocaine ingested by body packers) A suspected bezoar A commercially prepared solution of polyethylene glycol (which is nonabsorbable) and electrolytes, as sometimes used to cleanse the bowel for colonoscopy, is given at a rate of 1 to 2 L per hour for adults or at 25 to 40 mL / kg / h for children until the rectal effluent is clear; this process may require many hours or even days.