Studies with activated charcoal in the treatment of drug overdosage using the pig as an animal model

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.

Drug-encapsulated carbon (DECON): A novel platform for enhanced drug delivery

Current drug-delivery systems are designed primarily for parenteral applications and are either lipid or polymer drug conjugates. In our quest to inhibit herpes simplex virus infection via the compounds found in commonly used cosmetic products, we found that activated carbon particles inhibit infection and, in addition, substantially improve topical delivery and, hence, the efficacy of a common antiviral drug, acyclovir (ACV). Our in vitro studies demonstrate that highly porous carbon structures trapped virions, blocked infection and substantially improved efficacy when ACV was loaded onto them. Also, using murine models of corneal and genital herpes infections, we show that the topical use of drug-encapsulated carbon (DECON) reduced dosing frequency, shortened treatment duration, and exhibited higher therapeutic efficacy than currently approved topical or systemic antivirals alone. DECON is a nontoxic, cost-effective and nonimmunogenic alternative to current topical drug-delivery systems that is uniquely triggered for drug release by virus trapping.

Formulation of activated charcoal for per os administration to addicted subjects

The objective of this work was to develop a galenic form of activated charcoal appropriate for the needs of clinical toxicology. To preserve the adsorption capacity of charcoal, we developed an extemporaneous preparation of activated charcoal intended for clinical toxicology. To improve the wettability of activated charcoal, we used densification by wet granulation. The presence of a viscosity agent is necessary to ensure the homogeneity of the suspension and its adhesiveness on gastric mucous membrane. Five formulations with different viscosity agents were prepared, and their adsorption capacity, wettability, viscosity, and adhesiveness were studied.

Activated charcoal microcapsules and their applications

Activated charcoal, long known to the ancients as a substance of therapeutic value in a variety of maladies, has recently been "rediscovered" to be of great value in medical applications. Activated charcoal hemoperfusion is effective in blood purification for removal of various circulating toxic materials and waste metabolites, directly. However, particulate release and platelet adhesion prevent its continued clinical use. Polymeric coatings or microencapsulation of charcoal within polymers have improved their blood compatibility. Chitosan encapsulated activated charcoal (ACCB) beads have been extensively investigated in our group for the removal of various toxins such as urea, creatinine, uric acid, bilirubin, etc. This article highlights various methods of microencapsulation procedures of activated charcoal and the importance of this novel material for a variety of biomedical applications. Further, this review provides an insight to the future perspectives for using them in clinical practice.

Reduction of absorption of digoxin, phenytoin and aspirin by activated charcoal in man

The inhibitory effect of activated charcoal 50 g suspended in water on the absorption of digoxin, phenytoin and aspirin was studied in six healthy volunteers in a cross-over manner. The absorption of digoxin and phenytoin were almost completely prevented (about 98%) when activated charcoal was ingested immediately after the drug. The total absorption of aspirin was inhibited by 70%; with clear postponement of absorption and partial release of aspirin from the charcoal in the gut: The peak serum concentration of aspirin was reduced by 95% by charcoal. When activated charcoal was ingested 1 hour after the drugs the inhibition of absorption was considerably less. However, since the absorption of larger doses of the drugs is often slow, the administration of an adequate dose of activated charcoal will be of definite value in the treatment of acute intoxication, even if delayed for several hours.

Effect of activated charcoal on absorption of nortriptyline

The ability of 'Medicoal', a new effervescent, activated charcoal preparation, to adsorb nortriptyline, has been investigated both in vitro and in vivo. A single dose of the effervescent charcoal 30 min after a dose of 75 mg nortriptyline produced a 60% mean reduction in both peak plasma levels and nortriptyline availability in healthy volunteers. Multiple doses of the effervescent charcoal produced 70% mean reduction in peak nortriptyline levels and availabiltiy. Activated charcoal is recommended for the treatment of tricyclic antidepressant poisoning. In in-vitro tests, a 10 g packet of the effervescent preparation containing 5 g activated charcoal) had an adsorptive capacity of approximately 3000 mg nortriptyline, a dose not usually exceeded in most cases of trycyclic antidepressant overdose.