ivated charcoal in toxic emergencies involving these substances is not contraindicated. many poisonings involve multiple substances, therefore, actidose® with sorbitol and actidose®-aqua may be effective in adsorbing some or all of the ingested toxins. adsorption of a toxin by activated charcoal can occur anywhere in the gastrointestinal tract. however, to use actidose® with sorbitol or actidose®-aqua most effectively it is important to administer it as soon as possible to the victim of an ingested exposure. the longer the delay between the ingestion of the toxin and administration of activated charcoal, the less effective it will be. if syrup of ipecac is being used to produce emesis, administration of actidose® with sorbitol or actidose®-aqua is customarily delayed until 30 – 60 minutes after conclusion of emesis. in a study which used syrup of ipecac, 60 ml, activated charcoal did not interfere with the emetic effect of syrup of ipecac.23 if gastric lavage is being used to facilitate stomach evacuation a single dose of activated charcoal can be administered in the early stages of gastric lavage. if this technique is utilized, actidose®-aqua, which does not contain sorbitol, should be used. upon completion of gastric lavage actidose® with sorbitol can be instilled via the lavage tube. the only disadvantage to the use of activated charcoal in this fashion is that the gastric lavage returns will be black, thus making it difficult to evaluate what the patient ingested by visual examination. the primary advantage of this therapy is that activated charcoal can be administered early to the patient. the convenient packaging of actidose® with sorbitol and actidose®-aqua (except the 15gm/72ml size) in a squeeze bottle with a tapered nozzle expedites emergency treatment, allowing attachment to a gastric lavage tube and administration of contents. the most common application of activated charcoal is in acute toxic exposures where actidose® with sorbitol and actidose®-aqua can adsorb toxins thereby preventing their absorption. activated charcoal can also be used in some toxic emergencies when absorption is complete or exposure was via a parenteral route. this application usually involves repetitive or multiple doses of activated charcoal. multiple doses of activated charcoal may be useful in adsorbing toxins which undergo enterohepatic circulation.13 drugs which are subject to biliary secretion such as digitoxin are constantly secreted into the gastrointestinal tract and are reabsorbed resulting in prolonged toxicity. frequent doses of activated charcoal can adsorb those toxins thereby preventing their reabsorption and enhancing toxin elimination through the gastrointestinal tract. multiple dose activated charcoal is also used in what is termed gastrointestinal dialysis.14 there are only a limited number of toxins which may be eliminated by this method. clinical judgement and the toxin’s pharmacokinetic parameters must be considered to determine the applicability of this treatment which is not universally applicable.24 the toxin passively diffuses along a concentration gradient between blood which is perfusing the gastrointestinal tract and the luminal fluids. the multiple doses of activated charcoal adsorb the toxin thereby preventing its reabsorption further maximizing the concentration gradient which permits diffusion of even more toxin into the gastric lumen. compounds most effectively transferred by this mechanism are lipophilic, uncharged and not excessively bound to proteins. phenobarbital and theophylline are examples of toxins which can be eliminated more rapidly by this method.15,16 actidose® with sorbitol should not be used in each dose of the multiple dose activated charcoal regimen unless it is necessary to produce catharsis. actidose® with sorbitol contains sorbitol which may produce excessive catharsis and resultant fluid and electrolyte problems if used at each dosing interval (see precautions).9,25 actidose®-aqua should be used at dosage intervals when actidose® with sorbitol is not being used. cathartics should be used cautiously and only intermittently during multiple dose activated charcoal therapy. if catharsis of activated charcoal does not occur following the use of actidose® with sorbitol within 4 - 8 hours, an additional sorbitol dose of 1.5 gm/kg may be administered. or, if desired, a saline cathartic such as magnesium citrate may be used if the patient’s renal function is not impaired. actidose® with sorbitol and actidose®-aqua are formulated in palatable vehicles which eliminate the need to add additional taste or consistency enhancers. the use of supplementary chemicals, syrups, or dairy products should be avoided since their addition may compromise the adsorptive capacity of actidose® with sorbitol and actidose®-aqua.

2 much of the published scientific literature which studied the adsorptive capacity of activated charcoal was conducted using in vitro models. a considerable amount of the research may be invalid since the effects of physiologic ph were not taken into consideration or held constant. using research models which simulate the gastric environment, some toxins were not adsorbed by activated charcoal. this data was inappropriately extended to imply that activated charcoal did not adsorb a toxin and therefore had no efficacy in the management of that type of poisoning incident. however, the research failed to consider that the increased ph of the small intestine provides a receptive environment for the adsorption of the toxin by activated charcoal. activated charcoal will effectively adsorb acidic, alkaline and neutral substances (not to suggest use of activated charcoal in poisonings caused by corrosive agents2). the extent of adsorption will be dependent upon the relative solubility of the drug at a specified ph. the optimal dosage ratio of activated charcoal to toxin is described as 10:1.3,4,17,18 numerous factors contribute to and interfere with adsorptive capacity, therefore, the 10:1 ratio may not be valid in the clinical setting. furthermore, a primary application of activated charcoal is in adult patients who have intentionally ingested a toxin for drug abuse or suicidal purposes. these patients may not freely provide information about the substance or amount ingested, or have a decreased level of consciousness. under these conditions it is difficult to determine the ingestion history, making it impractical to use the 10:1 ratio. the 10:1 ratio is also impractical when large amounts of toxin have been ingested (i.e., an overdose of 50 gm of aspirin would then require 500 gm [1.1 lbs.] of activated charcoal). gastric contents may also compete with ingested toxins and compromise the adsorption of the toxins by activated charcoal.2 if activated charcoal is to be administered to a patient known to have ingested a large meal in close proximity to the time of treatment, a larger dose of activated charcoal may be appropriate. under appropriate physiologic conditions activated charcoal adsorbs toxins instantaneously. this adsorptive process is reversible and an equilibrium between free and bound toxin will exist. according to the law of mass action the amount of free drug decreases as the dose of activated charcoal increases. therefore, large doses of activated charcoal can favor the equilibrium toward greater toxin adsorption and efficacy. there is limited evidence that desorption of a toxin from activated charcoal may occur.19 therefore, there is a potential for toxin readsorption and enhanced toxicity. the current standard of care is to administer a cathartic with single doses of activated charcoal to hasten the elimination of the toxin/activated charcoal complex from the gastrointestinal tract.5 cathartics should be used with extreme care during multiple dose activated charcoal therapy and it is not recommended to use a cathartic with each dose of activated charcoal.5 sorbitol: sorbitol is a hexahydric sugar alcohol which primarily serves as an osmotic cathartic in actidose® with sorbitol.6 a secondary advantage of using sorbitol is as a palatability enhancer to decrease the innate gritty texture of activated charcoal and to provide a sweet vehicle to increase patient compliance. sorbitol is poorly absorbed during its transit through the gastrointestinal tract. absorbed sorbitol is metabolized by the liver and slowly converted to fructose. insulin is not necessary for intracellular transport of sorbitol, therefore customary cathartic doses can be safely used by patients with diabetes mellitus. as a hyperosmotic cathartic sorbitol produces a hygroscopic action resulting in increased water in the large intestine and increased intraluminal pressure which stimulates catharsis. studies have been conducted in healthy adult human volunteers using therapeutic amounts of activated charcoal and sorbitol.8,9 catharsis of activated charcoal occurred in an average of 1.0 - 1.5 hours and persisted for 8 - 12 hours. fourteen poisoned patients are reported in one series representing a wide range of toxins and dosages of sorbitol resulting in the onset of catharsis in an average of 7.7 hours.10 the onset of action may be expected to be longer in patients who have ingested toxins which decrease bowel motility, such as pharmacological agents and plants with anticholinergic properties, and drugs like narcotics.20 sorbitol does not compromise the adsorptive capacity of activated charcoal.11, 12