Physostigmine

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

Antidote

Pediatric

Physostigmine

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

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

Indications

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.

Dosage

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

Administration

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.

Monitoring

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)

References…