The action of activated charcoal on poisons in the digestive tract

Systematic review on the use of activated charcoal for gastrointestinal decontamination following acute oral overdose

INTRODUCTION

The use of activated charcoal in poisoning remains both a pillar of modern toxicology and a source of debate. Following the publication of the joint position statements on the use of single-dose and multiple-dose activated charcoal by the American Academy of Clinical Toxicology and the European Association of Poison Centres and Clinical Toxicologists, the routine use of activated charcoal declined. Over subsequent years, many new pharmaceuticals became available in modified or alternative-release formulations and additional data on gastric emptying time in poisoning was published, challenging previous assumptions about absorption kinetics. The American Academy of Clinical Toxicology, the European Association of Poison Centres and Clinical Toxicologists and the Asia Pacific Association of Medical Toxicology founded the Clinical Toxicology Recommendations Collaborative to create a framework for evidence-based recommendations for the management of poisoned patients. The activated charcoal workgroup of the Clinical Toxicology Recommendations Collaborative was tasked with reviewing systematically the evidence pertaining to the use of activated charcoal in poisoning in order to update the previous recommendations.

OBJECTIVES

The main objective was: Does oral activated charcoal given to adults or children prevent toxicity or improve clinical outcome and survival of poisoned patients compared to those who do not receive charcoal?  Secondary objectives were to evaluate pharmacokinetic outcomes, the role of cathartics, and adverse events to charcoal administration. This systematic review summarizes the available evidence on the efficacy of activated charcoal.

METHODS

A medical librarian created a systematic search strategy for Medline (Ovid), subsequently translated for Embase (via Ovid), CINAHL (via EBSCO), BIOSIS Previews (via Ovid), Web of Science, Scopus, and the Cochrane Library/DARE. All databases were searched from inception to December 31, 2019. There were no language limitations.  One author screened all citations identified in the search based on predefined inclusion/exclusion criteria. Excluded citations were confirmed by an additional author and remaining articles were obtained in full text and evaluated by at least two authors for inclusion. All authors cross-referenced full-text articles to identify articles missed in the searches. Data from included articles were extracted by the authors on a standardized spreadsheet and two authors used the GRADE methodology to independently assess the quality and risk of bias of each included study.

RESULTS

From 22,950 titles originally identified, the final data set consisted of 296 human studies, 118 animal studies, and 145 in vitro studies. Also included were 71 human and two animal studies that reported adverse events. The quality was judged to have a Low or Very Low GRADE in 469 (83%) of the studies. Ninety studies were judged to be of Moderate or High GRADE. The higher GRADE studies reported on the following drugs: paracetamol (acetaminophen), phenobarbital, carbamazepine, cardiac glycosides (digoxin and oleander), ethanol, iron, salicylates, theophylline, tricyclic antidepressants, and valproate. Data on newer pharmaceuticals not reviewed in the previous American Academy of Clinical Toxicology/European Association of Poison Centres and Clinical Toxicologists statements such as quetiapine, olanzapine, citalopram, and Factor Xa inhibitors were included. No studies on the optimal dosing for either single-dose or multiple-dose activated charcoal were found. In the reviewed clinical data, the time of administration of the first dose of charcoal was beyond one hour in 97% (n = 1006 individuals), beyond two hours in 36% (n = 491 individuals), and beyond 12 h in 4% (n = 43 individuals) whereas the timing of the first dose in controlled studies was within one hour of ingestion in 48% (n = 2359 individuals) and beyond two hours in 36% (n = 484) of individuals.

CONCLUSIONS

This systematic review found heterogenous data. The higher GRADE data was focused on a few select poisonings, while studies that addressed patients with unknown and or mixed ingestions were hampered by low rates of clinically meaningful toxicity or death.  Despite these limitations, they reported a benefit of activated charcoal beyond one hour in many clinical scenarios.

Potential misuse of ipecac

STUDY OBJECTIVE

To evaluate the use of ipecac by health care professionals.

DESIGN

A descriptive case series based on a one-year review of all calls to a poison center.

SETTING

A university hospital-affiliated regional poison center.

INTERVENTIONS

The use of ipecac was judged appropriate or inappropriate based on the consensus of three professionals associated with the poison center using predetermined contraindications.

MEASUREMENTS AND MAIN RESULTS

In 20% of cases in which ipecac was used, its use was inappropriate. The most common inappropriate situation was that too much time had elapsed from the time of ingestion. Among adults the most common contraindication was the ingestion of a substance known to cause altered mental status. Among children, the most common contraindication was the ingestion of a nontoxic substance or amount of substance. The poison center recommended ipecac inappropriately less often than emergency departments and usually in children ingesting a nontoxic substance. EDs recommended ipecac inappropriately with a broader range of contraindications and more often in adults.

CONCLUSION

Ipecac has potentially adverse consequences and should not be used reflexively. Providers of emergency care should be educated about possible contraindications to its use.

Management of toxicoses

This article provides information on the detoxification of and supportive care for poisoned animals. Involved are measures to control life-threatening manifestations of toxicoses, to remove agents from the digestive tract, skin, or eyes, and to promote removal of systemically absorbed toxicants. The use of these methods is often of paramount importance in an effort to limit organ damage and to enable a poisoned animal to survive.

Oral activated charcoal in the treatment of intoxications. Role of single and repeated doses

Activated charcoal has an ability to adsorb a wide variety of substances. This property can be applied to prevent the gastrointestinal absorption of various drugs and toxins and to increase their elimination, even after systemic absorption. Single doses of oral activated charcoal effectively prevent the gastrointestinal absorption of most drugs and toxins present in the stomach at the time of charcoal administration. Known exceptions are alcohols, cyanide, and metals such as iron and lithium. In general, activated charcoal is more effective than gastric emptying. However, if the amount of drug or poison ingested is very large or if its affinity to charcoal is poor, the adsorption capacity of activated charcoal can be saturated. In such cases properly performed gastric emptying is likely to be more effective than charcoal alone. Repeated dosing with oral activated charcoal enhances the elimination of many toxicologically significant agents, e.g. aspirin, carbamazepine, dapsone, dextropropoxyphene, cardiac glycosides, meprobamate, phenobarbitone, phenytoin and theophylline. It also accelerates the elimination of many industrial and environmental intoxicants. In acute intoxications 50 to 100g activated charcoal should be administered to adult patients (to children, about 1 g/kg) as soon as possible. The exceptions are patients poisoned with caustic alkalis or acids which will immediately cause local tissue damages. To avoid delays in charcoal administration, activated charcoal should be a part of first-aid kits both at home and at work. The 'blind' administration of charcoal neither prevents later gastric emptying nor does it cause serious adverse effects provided that pulmonary aspiration in obtunded patients is prevented. In severe acute poisonings oral activated charcoal should be administered repeatedly, e.g. 20 to 50g at intervals of 4 to 6 hours, until recovery or until plasma drug concentrations have fallen to non-toxic levels. In addition to increasing the elimination of many drugs and toxins even after their systemic absorption, repeated doses of charcoal also reduce the risk of desorbing from the charcoal-toxin complex as the complex passes through the gastrointestinal tract. Charcoal will not increase the elimination of all substances taken. However, as the drug history in acute intoxications is often unreliable, repeated doses of oral activated charcoal in severe intoxications seem to be justified unless the toxicological laboratory has identified the causative agent as not being prone to adsorption by charcoal. The role of repeated doses of oral activated charcoal in chronic intoxication has not been clearly defined.(ABSTRACT TRUNCATED AT 400 WORDS)

Therapeutic efficacy of superactive charcoal in rats exposed to oral lethal doses of T-2 toxin

Superactive charcoal, a compound known to complex with many toxins, was evaluated in this study for its effectiveness in preventing death in rats given an oral lethal dose of 8 mg/kg body weight of T-2 toxin. The median effective dose of oral superactive charcoal in preventing deaths in rats was 0.175 g/kg body weight. Concurrent use of cathartics, such as sorbitol, magnesium sulfate and sodium sulfate, to facilitate removal of the superactive charcoal:T-2 toxin complex formed in vivo did not enhance the survival rates of rats. One gram per kilogram body weight oral superactive charcoal enhanced survival times and survival rates in rats given 8 mg/kg of T-2 toxin as late as 3 hr after the T-2 toxin was administered. Some benefit in survival rate may be derived from giving the superactive charcoal as late as 5 hr after the T-2 toxin.

Gastrointestinal decontamination for acute poisoning

Gastric decontamination remains an important element in the therapy of pediatric poisoning; however, several issues remain unresolved. Additional studies, particularly in the clinical setting, are necessary to establish optimal therapeutic recommendations. Based on the data presented in this review, the following general recommendations can be made for gastric decontamination in children: If it is necessary to remove an ingested toxin, ipecac syrup is the preferred method if contraindications to its use are not present. The dose should be 30 ml in children older than 1 year of age and 10 ml in children 6 to 12 months of age. Pending further studies, the use of emetics in children younger than 6 months of age cannot be generally recommended, particularly in the home setting. Gastric lavage should be considered to be of very limited use in pediatric patients. Lavage using small nasogastric tubes, except under special circumstances, is nonproductive and cannot be advocated. If it must be used, a large-bore orogastric hose should be used. Administration of activated charcoal prior to lavage should be considered. In situations in which prompt induction of emesis is not possible or contraindications to emesis exist, activated charcoal followed by, or mixed with, a cathartic (preferably sorbitol) should be used as an alternative to removal of gastric contents. Patients with significant symptoms from ingestion requiring hospitalization should receive repeat doses of charcoal and cathartic until symptoms resolve. Activated charcoal should be given in conjunction with other appropriate therapies. Although the data to substantiate this recommendation are limited, particularly in pediatric patients, it is a benign therapy that holds promise of increasing drug elimination.

Management of acutely poisoned patients without gastric emptying

During an 18-month period, 592 acute oral drug overdose patients were studied prospectively in a controlled, randomized fashion to determine the efficacy of gastric emptying procedures in altering clinical outcome. Patients presenting on even-numbered days had no gastric emptying procedures performed, and they were compared to patients presenting on odd-numbered days who received either syrup of ipecac or gastric lavage. Patients were carefully followed for evidence of subsequent clinical improvement or deterioration after initial management. Syrup of ipecac did not significantly alter the clinical outcome of patients who were awake and alert on presentation to the emergency department (ED). Gastric lavage in obtunded patients led to a more satisfactory clinical outcome (P less than .05) only if performed within one hour of ingestion. Gastric emptying procedures in the ED for initial treatment of drug overdose are generally not of benefit unless gastric lavage is performed within one hour of ingestion in obtunded patients.

Comparison of activated charcoal and gastric lavage in the prevention of aspirin absorption

Effectiveness of initial treatment of aspirin (ASA) overdosage was evaluated by comparing treatment with activated charcoal (AC) to treatment with gastric lavage in combination with AC. Dogs were used as subjects in four experimental groups. All subjects were administered an overdose of 500 mg/kg of ASA. Treatment was performed 30 minutes later on all groups except controls. Treatment with AC alone resulted in a 17% reduction (P greater than .05) of peak plasma salicylate levels compared with controls. When lavage preceded administration of AC, a 37% reduction (P less than .05) occurred. There was a 48% reduction (P less than .025) in plasma salicylate levels when lavage was preceded and followed by administration of AC. This study demonstrates that gastric lavage in combination with AC is more effective in reducing ASA absorption than AC given alone.

Evaluation of activated charcoal-sorbitol suspension as an antidote

Studies in rats were performed to evaluate the effect of sorbitol on the antidotal efficacy of activated charcoal against four test drugs and to investigate the influence of storage upon the antidotal effect of activated charcoal-sorbitol suspension. The antidotal potency of activated charcoal was not diminished by sorbitol solution 70% w/v. In fact, it was enhanced by the sorbitol solution, as indicated by greater decrease in peak tissue drug concentration, compared to the effect produced by activated charcoal in aqueous suspension. Furthermore, storage of activated charcoal in sorbitol for as long as 1 year did not reduce the antidotal-efficiency of the absorbent.

Assessment of the efficacy of activated charcoal following gastric lavage in acute drug emergencies

The efficacy of administering a slurry of 100 g of activated charcoal (AC) via the gastric tube following lavage was assessed in 25 treated and 37 control patients presenting to the emergency room with chemical evidence of sedative-hypnotics or aspirin in the blood. Efficacy was evaluated as the ability of AC to prevent further absorption as determined by subsequent blood drug concentration changes. Although fewer patients in the AC group showed increased blood drug concentrations, the differences were not statistically significant. Comparison of the mean percent change in blood drug concentrations at various times following treatment produced similar results. Comparisons using subgroups of patients based on the individual drugs, the treatment delay time, and entering functional decompensation showed significant benefit from AC only in the less symptomatic patients. Comparing these results with other studies demonstrating the unequivocal efficacy of early (e.g., 30 min) treatment, it is concluded that the use of AC following lavage may often be too late to benefit most patients. The authors suggest that AC be given in the home, emergency vehicle, or immediately upon admission.

An activated charcoal hemoperfusion system for the treatment of barbital or ethylene glycol poisoning in dogs

The efficacy of activated charcoal (AC) hemoperfusin therapy was studied in dogs acutely poisoned with lethal doses of barbital or ethylene glycol (EG). Two of three barbital-poisoned dogs treated with AC hemoperfusion survived; the dog tha died was only hemoperfused for 1.5 h. Although AC hemoperfusion of EG-poisoned dogs reduced the blood level of the toxicant considerably, this was not enough to effect survival. The use of AC hemoperfusion was an effective therapeutic measure for dogs poisoned with lethal doses of barbital. The use of the AC hemoperfusion system with existing drugs of therapy for EG poisoning may be beneficial.

Saline cathartics and saline cathartics plus activated charcoal as antidotal treatments

The results of this experimental study indicate that Na2SO4 reduces the gastrointestinal absorption of aspirin, but not that of pentobarbital, chlorpheniramine, or chloroquine. Activated charcoal (AC) and the combination of AC + Na2SO4 were effective in reducing gastrointestinal absorption of all four test drugs. The combination treatment was more effective than AC treatment in reducing gastrointestinal absorption of aspirin, pentobarbital, and chloroquine. We believe that saline cathartics should not be used in lieu of AC for treatment of poison ingestions, and their routine use to treat poison ingestion should be reevaluated. On the other hand, saline cathartics may be used in conjunction with AC to enhance the antidotal effect of the adsorbent.

Omission of pepsin from simulated gastric fluid in evaluating activated charcoals as antidotes

Although simulated gastric fluid USP calls for 3.2 g of pepsin/liter, most researchers omit pepsin when evaluating adsorbents. The present results show that, although pepsin adsorbs strongly to activated charcoal, it does not interfere significantly with the adsorption of a typical drug like sodium salicylate. Therefore, its omission is justified. Gastric mucin also had almost no effect on salicylate adsorption.

Drug overdosage in children

The epidemiology and prevention of drug overdosage in children is discussed. The emergency treatment of acute drug overdosage is outlined together with aspects of the intensive care management in relation to conscious state, convulsions, respiratory failure, circulatory failure and arrhythmias with some emphasis on tricyclic antidepressants.