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Action/Kinetics:
Reversible acetylcholinesterase inhibitor causing an increased concentration of acetylcholine at nerve endings; antagonizes anticholinergic drugs. Produces miosis, increased accommodation, and a decrease in intraocular pressure with decreased resistance to outflow of aqueous humor.
Onset, IV: 3-5 min.
Duration, IV: 1-2 hr.
t
1/2: 1-2 hr. No dosage alteration is necessary in clients with renal impairment.
Uses:
Overdosage due to cholinergic blocking drugs (e.g., atropine) and tricyclic antidepressant overdosage. Friedreich's and other inherited ataxias (FDA has granted orphan status for this use).
Investigational: Treat delirium tremens (DTs) and Alzheimer's disease. May also antagonize the CNS depressant effect of diazepam.
Contraindications:
Acute-angle glaucoma, history of retinal detachment, ocular hypotension, asthma, epilepsy, parkinsonism, gangrene, diabetes, CV disease, GI or GU tract obstruction, spastic GI conditions, vasomotor instability, severe bradycardia or hypotension, recent MI, lactation, in those receiving choline esters or depolarizing neuromuscular blocking drugs.
Special Concerns:
Use with caution during lactation. Reserve systemic use in children for life-threatening situations only. Benzyl alcohol, found in the parenteral product, may cause a fatal "gasping syndrome" in premature infants. The parenteral form also contains sulfites that may cause allergic reactions.
Side Effects:
Nausea, GI discomfort, diarrhea, hypotension, bronchial constriction, increased salivation. If IV administration is too rapid, bradycardia, hypersalivation, breathing difficulties, and
seizures may occur.
Overdose Management:
Symptoms: Cholinergic crisis.
Treatment: IV atropine sulfate:
Adults: 0.4-0.6 mg;
infants and children up to 12 years of age: 0.01 mg/kg q 2 hr as needed (maximum single dose should not exceed 0.4 mg). A short-acting barbiturate may be used for seizures not relieved by atropine.
Drug Interactions:
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Anticholinesterases, systemic / Additive effects
toxicity
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Succinylcholine /
Risk of respiratory and CV collapse
How Supplied:
Physostigmine salicylate:
Injection: 1 mg/mL.
Dosage
?IM, IV
Anticholinergic drug overdose.
Adults, IM, IV: 0.5-2 mg at a rate of 1 mg/min; may be repeated if necessary.
Pediatric, IV: 0.02 mg/kg IM or by slow IV injection (0.5 mg given over a period of at least 1 min). Dose may be repeated at 5-10 min if needed to a maximum of 2 mg if no toxic effects are manifested.
Postanesthesia.
0.5-1 mg given IM or by slow IV (less than 1 mg/min). May be repeated at 10- to 30-min intervals to attain desired response.
