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Poisoning Information for the Public & Health Care Professionals
Last updated: 01/2021


Anticholium; 0.4 mg/mL (2 mg / 5 mL amp) physostigminsalicylat

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Anticholium; 0.4 mg/mL (2 mg / 5 mL amp) physostigminsalicylat

ALERT: Contact the Atlantic Canada Poison Centre before using physostigmine.


  • Agitation and delirium due to anticholinergic toxicity
  • Contraindicated in presence of:
    • TCA overdose
    • QRS widening (>100 ms), QTc > 500 ms, or any other cardiac conduction abnormality (AV or intraventricular)
  • Generally not recommended for mixed drug or unknown poisoning.
  • Often used in conjunction with benzodiazepines. The use of physostigmine may reduce the need for high doses of benzodiazepines. 


  • IV Direct:  0.02 mg/kg (maximum 0.5 mg) IV over 5 minutes
    • Repeat dose as needed every 10 minutes until desired clinical effect (maximum 2 mg in the first hour)
    • Additional doses may be required for relapse after initial clinical improvement due to short duration of action of physostigmine


ALERT: Atropine should be available at the bedside and titrated to effect should excessive cholinergic toxicity develop.  A dose of atropine at half the physostigmine dose is recommended.

  • IV Direct: Administer undiluted solution (0.4 mg/mL)
  • Doses less than 0.2 mg (0.5 mL) can be diluted with sodium chloride 0.9% to a total volume of 0.5 mL to facilitate administration. 
  • Onset of action occurs between 5 and 10 minutes after IV administration and the duration varies between 30 min and 5 hours depending on the severity of the anticholinergic poisoning to be reversed. Additional doses of physostigmine may be required. 
  • NOTE:  To minimize drug wastage, it is recommended that two doses be immediately prepared using the opened ampoule. 


  • Cardiac monitoring
  • Neurological examination  

Endpoint of therapy

Sustained resolution of agitation and delirium. 

Compatibility, Stability

  • Compatible with sodium chloride 0.9%. 
  • Protect from light. 

Potential Hazards of Administration

  • Muscarinic cholinergic effects such as bradycardia, atrioventricular block, asystole, nausea, vomiting, miosis, salivation, bronchorrhea, bronchospasm.
  • Generalized convulsions, muscle weakness and fasciculation if there is significant stimulation of nicotinic cholinergic receptors.
  • Rapid administration may cause bradycardia, hypersalivation leading to respiratory difficulty, and seizures. 
  • Use caution in patients with underlying conditions including reactive airway disease, peripheral vascular disease and intestinal or bladder obstruction. 

Suggested stocking: 4 mg (2 x 2 mg vials)