Edrophonium

INDICATIONS:

	Neuromuscular blockade, reversal after non-depolarizing agents.
	Evaluation of 'dual block' produced by succinylcholine.
	Diagnosis of myasthenia gravis.
	Differentiation of cholinergic from myasthenic crises.
	Paroxysmal atrial tachycardia.

CLASS: Anticholinesterase (cholinergic) agent.

MODE OF ACTION: Quaternary ammonium anticholinesterase producing reversible inhibition of acetylcholinesterase. More rapid onset than neostigmine. Vagotonic effect appears early.

ONSET: IV 30-60 s, peak effect 1-5 min. Assess residual neuromuscular blockade (NMB) with nerve stimulator.

DURATION: IV half-time 111 min (0.5 mg/kg dose); in anephric patients 206 min.

CLEARANCE: Hepatic metabolism, renal clearance accounts for 75% of elimination.

ADULT DOSE:

	Reversal of neuromuscular blockade: 0.5-1.0 mg/kg slow IV (maximal dose 40 mg), with atropine 0.007-0.015 mg/kg IV or glycopyrrolate 0.01 mg/kg IV.
	Evaluation of 'dual block' produced by succinylcholine: 0.1-0.2 mg/kg IV.
	Paroxysmal atrial tachycardia: 2 mg slow IV every 1-2 min, maximum 10 mg.
	Differentiation of cholinergic from myasthenic crises: 1 mg slow IV; may repeat after 1 min, maximum dose 10 mg.
	Diagnosis of myasthenia gravis: 2 mg IV test dose over 30 s; if no response, 8 mg IV given 45 s later.

PEDIATRIC DOSE:

	Reversal of neuromuscular blockade: 1 mg/kg slow IV preceded by atropine 0.02 mg/kg IV.
	Diagnosis of myasthenia gravis: 0.04 mg/kg/dose IV single dose; maximal dose - 1 mg < 34 kg, 2 mg > 34 kg (consult pediatric neurologist).

NEONATAL DOSE: Diagnosis of myasthenia gravis: 0.1 mg  IV single dose (consult pediatric neurologist).

CAUTION: Asthma, bradycardia, recent myocardial infarction, epilepsy, hyperthyroidism, peptic ulcer. Administration to patients with an absolute contraindication to succinylcholine (e.g. myotonia). Beta-adrenergic blockade. Reduce dose in patients with chronic renal failure.

CONTRAINDICATIONS: Hypersensitivity to edrophonium or sodium sulfite. Gastrointestinal or genitourinary tract obstruction. See neostigmine for details.

INTERACTIONS: See neostigmine for details.

ADVERSE REACTIONS: Cholinergic crisis due to edrophonium overdose. See neostigmine for details.

PREGNANCY: Category C

COMMENTS:

	When initiating reversal, 1 mg/kg IV is required if twitch depression > 90%.
	Neostigmine is more effective than either edrophonium or pyridostigmine in antagonizing intense neuromuscular block.
	The onset time and lesser requirements of atropine makes its use more appropriate with edrophonium. Some advocate the practice of administering atropine before edrophonium, as in pediatric use.
	Where edrophonium is administered as the sole drug, atropine (or glycopyrrolate) must always be available for immediate use to prevent muscarinic cholinergic effects.
	Edrophonium does not produce marked and prolonged inhibition of plasma cholinesterase activity, as is the case with neostigmine.