• 
• 

Three Part Question

In [patients who ingested toxic levels of a drug more than 2 hours before], is [administration of activated charcoal] still [effective in preventing systemic absorption of the drugs]?

Clinical Scenario

A 35 year old man presented to the emergency department 3 hours after ingesting 25 tablets of 200mg hydroxychloroquine sulfate in a suicide attempt. Should activated charcoal still be administered?

Search Strategy

Pubmed 1991-2024
Search keywords [activated charcoal], [overdose], [delayed activated charcoal administration], [effectiveness].

Search Outcome

37 papers were found on Pubmed, 3 papers were relevant and of sufficient quality for inclusion, 11 papers were not reflective of the outcome in question as it focused on specific drug overdoses or of insufficient quality for inclusion, 13 papers were irrelevant.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
R Green 2001 United States	10 volunteers	A randomised crossover study How long after drug ingestion is activated charcoal still effective?	Our data do not support the administration of activated charcoal as a gastrointestinal decontamination strategy beyond 1 hour after drug overdose.		Small sample size
P J Yeates 24 December 2001 United Kingdom	Healthy volunteers	An open randomized-order four-way crossover study	no evidence of efficacy for activated charcoal when administered after an interval of more than 2 h.		Results in healthy volunteers cannot be extrapolated directly to poisoned patients.
David N. Juurlink 26 September 2015 United Kingdom	n/a	a reappraisal	Although volunteer studies demonstrate that the reduction of drug absorption decreases to values of questionable clinical importance when charcoal is administered at times greater than 1 h, the potential for benefit after 1 h cannot be excluded. The potential benefit of delayed SDAC in a modified-release overdose was illustrated, for example, in a volunteer study in which SDAC given 4 h after ingestion of 2.9 g of enteric-coated acetylsalicylic acid reduced absorption by 57%.

Comment(s)

Oral activated charcoal is effective at reducing drug absorption in drug overdose when administered within 1 h of drug ingestion. However, there is less data on the efficacy in delayed administration of activated charcoal for patients presenting more than 1 hour after drug ingestion. The answer to this may also differ for different drugs, for example there is potential benefit in delayed administration in overdose of slow-release preparations. The relevant studies found all had very minimal sample size and thus there is no clear answer.

Clinical Bottom Line

Single dose activated charcoal is an important therapeutic option for acute drug overdose and is widely known to be effective when administered up to 1 hour of drug ingestion. However, there is no clear answer to the effectiveness of delayed administration in patients presenting more than 1 hour after drug ingestion as many different factors must be considered such as the bioavailability of the specific drug ingested. In conclusion, whether or not to administer activated charcoal requires clinical judgement involving a global assessment of several patient and circumstance specific factors.

References

1. R Green How long after drug ingestion is activated charcoal still effective? Journal of Toxicology
2. P J Yeates Effectiveness of delayed activated charcoal administration in simulated paracetamol (acetaminophen) overdose British Journal of Clinical Pharmacology
3. David N. Juurlink Activated charcoal for acute overdose: a reappraisal British Journal of Clinical Pharmacology