physostigmine
Classes: Anticholinergic Toxicity Antidotes; Acetylcholinesterase Inhibitors, Peripheral
Dosing and uses of Physostigmine
Adult dosage forms and strengths
injectable solution
- 1mg/mL
Anticholinergic Toxicity
Initial: 0.5-2 mg slow IVP (not to exceed 1 mg/min); keep atropine nearby for immediate use
If no response, repeat q20min PRn
If initial dose effective, may give additional 1-4 mg q30-60min PRn
Rarely used; indicated only when life-threatening symptoms related to anticholinergic toxicity
Useful for diagnostic as opposed to therapeutic reasons
Pediatric dosage forms and strengths
injectable solution
- 1mg/mL
Anticholinergic Toxicity
0.02 mg/kg/dose slow IVP (not to exceed 0.5 mg/min); may repeat q5-10min PRN, not to exceed cumulative dose of 2 mg
Physostigmine adverse (side) effects
Frequency not defined
Seizure
Cardiovascular collapse
Bradycardia
Bronchospasm
Dyspnea
Diaphoresis
Diarrhea
Hyperperistalsis
Cholinergic Sx
Hallucinations
Warnings
Contraindications
Salicylate allergy
Asthma, gangrene, diabetes, cardiovascular disease, mechanical obstruction of the intestinal or urogenital tract or any vagotonic state
Concurrency with choline esters or depolarizing neuromuscular blocking agents
Cautions
Keep atropine ready for potential cholinergic sx
Pregnancy and lactation
Pregnancy category: C
Lacation: Unknown if excreted in breast milk; caution advised
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Physostigmine
Onset: 5-10 min
Duration: 30-60 min
Mechanism of action
Indirect acting parasympathomimetic via inhibition of acetylcholinesterase