Physostigmine

Indications: 

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

Formulation:

• 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.