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Three Part Question

In [patients with opioid poisoning] does [delayed administration of activated charcoal] [reduce absorption of the poison?]

Clinical Scenario

A twenty year-old lady presents to the Emergency Department claiming to have taken 100 co-codamol tablets two hours ago. The guidelines suggest that activated charcoal is of no benefit at this stage. However, you are aware that opioids encourage gastric stasis and wonder if there is any evidence that activated charcoal is still of benefit to this patient.

Search Strategy

Medline using OVID interface 1966 - June 2003
[exp Narcotics OR opioid.mp OR opiate.mp OR co-proxamol.mp OR co-codamol.mp] AND [exp charcoal OR activated charcoal.mp] limit to (human and english language)

Search Outcome

34 papers were identified, of which only one was relevant to the question

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Laine K, Kivisto KT et al 1997 Finland	32 healthy volunteers, each receiving 100mg pholcodeine, randomised into four groups to receive no activated charcoal, 25g immediately, 25g at 2 hours or 25g at 5 hours. The 5-hours group also received a further 10g activated charcoal every 12 hours for 84 hours	PRCT	Absorption of pholcodeine	Significant reduction when given at 0 and 2 hours	Small numbers (32 patients in total)
			Maximum serum pholcodeine level	Significantly lower when given immediately; lower but not significant in 2-hour group

Comment(s)

There is a paucity of evidence with regard to this topic and no clinical trials have looked at codeine, dextropropoxyphene, co-codamol or co-proxamol overdose and delayed activated charcoal administration. The only clinical trial to be done in this area used pholcodine, a weak opioid. This trial demonstrated a reduction in absorption when charcoal was administered after 2 hours. Reduction of absorption of the poison may be particularly desirable in cases involving preparations containing opioid and paracetamol, as such overdoses are more likely to lead to significant harm. Dextropropoxyphene (as in co-proxamol), taken in relatively small doses may lead to cardiotoxicity, convulsions and death. Any reduction in the absorption of this poison by delayed activated charcoal would be particularly desirable.

Clinical Bottom Line

Delayed activated charcoal should be considered in the case of pholcodine overdose. Although there is no direct evidence for the efficacy of delayed activated charcoal with other opioids, the available evidence does suggest that it should also be considered.

References

1. Laine K, Kivisto KT, Ojala-Karlsson P, Neuvonen PJ. Effect of Activated Charcoal on the Pharmacokinetics of Pholcodine, with Special Reference to Delayed Charcoal Ingestion. Therapeutic Drug Monitoring 1997;19(1):46-50.