Liverpool Hospital Emergency Department


  • Severe Anticholinergic Toxidrome caused by a pure anticholinergic drug under  clinical advice from a toxicologist
  • Short acting IV cholinesterase inhibitor that crosses the BBB. 


  • Intravenous 2mg (5ml) 

Dosage and Administration: 

  • Administer in a resuscitation area: risk of bradydysrhythmias / bronchospasm
  • 0.5mg (0.01mg/kg up to 0.5mg) IV over 5 minutes and repeat after 15 minutes if  there is no response to a maximum of 2mg in a 60-minute period
  • Avoid in patients with bradycardia and bronchospasm
  • Response: Resolution of the delirium 

Side Effects: 

  • Bradycardia
  • Bronchospasm
  • Nausea / Vomiting / Diarrhoea
  • Avoid in TCA overdose or non-pure anticholinergic overdose as serious adverse  effects have occurred including seizures and arrhythmias. 

Pit Falls: 

  • Redosing may be required as physostigmine is short-acting (1-2 hours)
  • Consider alternative agents for control of agitation if physostigmine is not available  including benzodiazepines and droperidol.
  • Large doses of these agents might be  required.