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

Presence of peripheral or central antimuscarinic effects without significant QRS or QT prolongation

* 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

* Don’t be Afraid of Physostigmine

Nice Review Article

* Dawson et al.

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: