That diphenhydramine OD that is driving you up a wall, the seroquel OD that can't give you any history and is sucking up all of your benzos–there is a solution! Physostigmine used to be standard care, but then after a scare with TCA ODS, its use by non-tox folks markedly diminished.
Bryan Hayes
Today I am lucky to have Bryan Hayes, the Pharm ER Tox Guy, back on the show to discuss Physostigmine for anti-cholinergic toxicity. Bryan is a ED pharmacist with a fellowship in toxicology. He tweets as PharmERToxGuy and blogs at Academic Life in EM and on his own site, pharmertoxguy.com.
Use in Anticholinergic Poisoning
Physostigmine controlled agitation and reversed delirium in in 96% and 87% of patients, respectively (Ann Emerg Med 2000;35(4):374-81.). Benzodiazepines controlled agitation in only 24% of patients but were ineffective in reversing delirium.
Indications
- Peripheral: dry mucosa, dry skin, flushed face, mydriasis, hyperthermia, decreased bowel sounds, urinary retention, and tachycardia
- Central: agitation, delirium, hallucinations, seizures, and coma
Hayes' Algorithm
- Physostigmine 1 mg IV over 5 minutes (mixed in 50 mL NS), can be repeated x 1, ~10-15 minutes after the 1st dose. Continuous cardiac monitoring and atropine at the bedside.
Contraindications (from package insert)
- Reactive airway disease, peripheral vascular disease, intestinal or bladder obstruction, intraventricular conduction defects, and AV block and in patients receiving therapeutic doses of choline esters and succinycholine.
- Known or suspected TCA OD
The Post on Bryan's Site
Nice Review Article
Some Literature
- 1980's cases of asystole in TCA poisoning: https://www.ncbi.
nlm.nih.gov/pubmed/7001962 - 1998 case of 15 year old with asystole in TCA poisoning: https://www.ncbi.
nlm.nih.gov/pubmed/9655671 - Physo clearly beneficial over benzos: https://www.ncbi.nlm.
nih.gov/pubmed/10736125 - Physo associated with less ICU admissions: https://www.ncbi.
nlm.nih.gov/pubmed/20405266 - 2017 poison center study: https://www.ncbi.nlm.
nih.gov/pubmed/28703024
Some FOAM
Updates
References
Arens AM et al. Adverse effects of physostigmine. J Med Toxciol. Feb 11. doi:
Additional New Information
More on EMCrit
- Anticholinergic intoxication(Opens in a new browser tab)
- Podcast 98 – Cyclic (Tricyclic) Antidepressant Overdose(Opens in a new browser tab)
- Sodium Channel Blocker Toxicity (including tricyclic antidepressants)(Opens in a new browser tab)
Additional Resources
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Professor
Nassau University Medical Center
No conflicts of interest (coi).
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Recently I had a case of Mandrake poisoning. The root was eaten by a young woman in order to increase fertility. Soon after, she developed signs of anti-cholinergic poisoning, mainly dryness, urinary retention and sinus tachycardia. In addition, she became severely agitated, with restlessness and visual hallucinations. We gave her Diazepam in order to control the agitation, so she slept for a while but due to renewed signs of delirium, she got 1 mg of Physostigmine and than another one, which worked like magic. She became coherent and cooperative, after the first dose. Later, she was discharged intact from the… Read more »
I’ve used this effectively in severely symptomatic diphenhydramine and scoplamine intoxications. Curious about its being ‘contraindicated in TCA overdoses’… that must be from very old data (or a few case reports?). Keep up the great work!
I wonder if it might be worth giving a dose of the muscle relaxant reversal combination of glycopyrronium and neostigmine as a test dose.. It will last for a few minutes, prevent any Bradycardias and inform you as to whether it will help. Most of our ODs are mixed and it is difficult to decide what to reverse safely!
Jo
“Alright… pretend I’m an idiot”. I love it.
Great ‘cast. I was always taught to fear the Physo… no longer. Thanks for the deep dive.