Keywords: physostigmine, lorazepam, anticholinergic toxicity, delirium (PubMed Search)
Antimuscarinic agents (e.g. diphenhydramine) are one of the commonly ingested substances in the US. Lorazepam is frequently used to treat delirium and agitation associated with antimuscarinic toxicity. Although physostigmine is also effective, its use is infrequent due to concerns of safety and provider’s limited experience with physostigmine.
A small blinded randomized clinical trial was conducted to compare physostigmine vs lorazepam for the treatment of antimuscarinic toxicity -delirium/agitation.
Plus administration of lorazepam (0.05 mg/kg) IV bolus (max 2 mg) every 2 hours as needed for continued agitation or delirium (at the discretion of treatment team)
Delirium and agitation were assessed by Confusion Assessment Method for the Intensive Care Unit score (CAM-ICU) and Richmond Agitation Sedation Score
Study duration: March 20, 2017 to June 30, 2020
Antimuscarinic agent ingested
Proportion of subject with delirium by CAM-ICU
Prior to first bolus (p >0.99)
After 1st bolus (p=0.01)
End of 4 hr infusion (p <0.001)
No adverse events noted in both group
Wang GS et al. A randomized trial comparing physostigmine vs lorazepam for treatment of antimuscarinic (anticholinergic) toxidrome. Clin Toxicol (Phila.) 2020. Dec 9. Online ahead of print. https://doi.org/10.1080/15563650.2020.1854281