physostigmine

Dosing and uses of Physostigmine

• Adult
• Pediatric

 

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