II. Indications
- Incapacitating Agent exposure (e.g. BZ, Agent 15)
- Anticholinergic Overdose (e.g. Diphenhydramine, Atropine)
III. Pharmacokinetics
- Reversibly binds Acetylcholinesterase (short-acting Acetylcholinesterase Inhibitor)
- Related to Pyridostigmine
- Lasts only 30 to 60 minutes
- May require frequent redosing as below
IV. Routes
- Intramuscular
- Adults: 0.05 mg/kg
- Child: 0.02 mg/kg
- Intravenous
- Dose: 0.02 mg/kg up to 1-2 mg
- Available in 2 mg/2 ml vials
- Dilute one 2 mg Physostigmine vial in 8 cc NS within a 10 cc syringe and infuse slowly
- Infuse over 2-10 minutes or slower and may repeat every 30 minutes (as often as every 10-20 min)
- Risk of Seizure if infused too quickly
- Dose: 0.02 mg/kg up to 1-2 mg
- Oral: 60 mcg/kg (bitter taste, dilute in juice)
V. Protocol: Example in Adults
- Initial: 2-3 mg IM or 2 mg slow IV (see above)
- Repeat: every 30-60 minutes prn depressed mental status
- Maintenance: 2-4 mg IV slowly every 2-4 hours prn
- Taper: Slowly taper over hours to 4-5 days
VI. Precautions
- Consult toxicology (esp. if more than one dose is needed)
VII. Adverse Effects
-
Bradycardia (common, related to increased vagal tone)
- Atropine 0.5 to 1 mg may be given to counter significant Bradycardia or bronchorrhea
- Bronchorrhea
-
Vomiting
- Consider pretreatment with Ondansetron
- See Cholinergic Toxicity
VIII. Contraindications
- Cardiac conduction abnormality (Obtain EKG prior to administration)
- Bradycardia
- Intraventricular conduction delay
- AV Nodal block
- Tricyclic Overdose
- Uncontrolled Asthma or Wheezing
- Seizure Disorder
IX. References
- (2016) CALS Manual, 14th ed, 1:133
- Orman and Hatten in Herbert (2016) EM:Rap 16(4): 6