Saturday, September 29, 2018

Activated Charcoal and Beta Blocker Overdose: Clinical Decision Making and the Risks of Dichotomization

This very nice case report in the current issue of the Annals of the ATS is an opportunity to discuss rational clinical decision making.  The authors did almost everything that I would have done in this case and it is a lovely discussion of this toxidrome and its treatment.  There is just one simple and apparently inconsequential decision that I disagree with and I intend to use it as a springboard to discuss rational clinical decision making.

The young woman had a multidrug overdose including metoprolol succinate, extended release.  She presented in shock.  The authors state "Gastrointestinal decontamination was not performed because her ingestion was suspected to have occurred several hours before admission" [emphasis mine].  I have already in an early post on this blog, discussed the inadequacy of the existing data and experimental models on the timing of charcoal administration, which interested readers can read about here.

Studies of the timing of Activated Charcoal (AC) administration use normal volunteers taking therapeutic doses of drugs (for ethical reasons).  We have inadequate data on the speed of absorption of drugs in people who are shocked or who take very large doses of drugs, or extended release drugs.  To dichotomize the efficacy of AC by a bright line of 30 or 60 or even 120 minutes is a gross oversimplification of reality that belies overconfidence in the existing data and experimental models.  This patient took a large dose of a sustained release medication and at some point became shocked presumably causing splanchnic vasoconstriction.  She also took Tramadol and other medications which may slow gut motility via anticholinergic or other effects.  And there may be other unknowns - other medications she took that slowed absorption of the sustained release metoprolol that we don't even know about.