EDROPHONIUM CHLORIDE
(ed-roe-foe'nee-um)
Enlon, Reversol, Tensilon
Classifications: autonomic nervous system agent; cholinergic (parasympathomimetic) cholinesterase inhibitor
Prototype: Neostigmine
Pregnancy Category: C
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10 mg/mL injection
Indirect-acting cholinesterase inhibitor similar to neostigmine that is rapidly reversible. Acts as antidote to curariform
drugs by displacing them from muscle cell receptor sites, thus permitting resumption of normal transmission of neuromuscular
impulses. Like neostigmine, it prolongs skeletal muscle relaxant action of succinylcholine chloride and decamethonium bromide.
Acts as antidote to curariform drugs by displacing them from muscle cell receptor sites, thus permitting resumption of normal
transmission of neuromuscular impulses.
Differential diagnosis and as adjunct in evaluation of treatment requirements of myasthenia gravis, for differentiating myasthenic
from cholinergic crisis, and to reverse neuromuscular blockade produced by overdosage of nondepolarizing skeletal muscle relaxants,
e.g., tubocurarine, gallamine. Not recommended for maintenance therapy in myasthenia gravis because of its short duration
of action.
To terminate paroxysmal atrial tachycardia, as an aid in diagnosing supraventricular tachyarrhythmias, and to evaluate function
of demand pacemakers.
Hypersensitivity to anticholinesterase agents; intestinal and urinary obstruction. Safety during pregnancy (category C) or
lactation is not established.
Bronchial asthma; cardiac arrhythmias; patients receiving digitalis.
Edrophonium Test for Myasthenia Gravis
Adult: IV Prepare 10 mg in a syringe; inject 2 mg over 15–30 sec, if no reaction after 45 sec, inject the remaining 8 mg, may repeat
test after 30 min IM Inject 10 mg, if cholinergic reaction occurs, retest after 30 min with 2 mg to rule out false-negative reaction
Child: IV
 34 kg, 1 mg, if no response after 45 sec, dose may be titrated up to 5 mg IM 2 mg IV
>34 kg, 2 mg, if no response after 45 sec, dose may be titrated up to 10 mg IM 5 mg
Infant: IM 0.5–1 mg
Evaluation of Myasthenia Treatment
Adult: IV 1–2 mg administered 1 h after last PO dose of anticholinesterase medication
Curare Antagonist
Adult: IV 10 mg administered over 30–45 sec, may repeat q5–10 min as needed up to 40 mg
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Note: Have antidote (atropine sulfate) immediately available and facilities for endotracheal intubation, tracheostomy, suction,
assisted respiration, and cardiac monitoring for treatment of cholinergic reaction.
| Intravenous PREPARE: Direct: May be given undiluted.
ADMINISTER: Direct:
USE for diagnosis of MG—Inject 2 mg (adult & child >34 kg) or 1 mg (child 34
kg) over 15–30 sec; if no reaction after 45 sec, inject additional 8 mg (adult) or titrate up to a total of 8 mg additional
(child >34 kg) or titrate in 1 mg increments up to a total of 4 mg additional (child 34
kg), may repeat test after 30 min. If cholinergic reaction (increased muscle weakness) is obtained after initial 1 or 2 mg,
discontinue test and give atropine IV (as ordered).
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Note: Some clinicians recommend giving a 1–2 mg test dose of edrophonium to older adult patients, to those with history of
heart disease or who take digitalis, and possibly to all patients.
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Body as a Whole: Severe adverse effects uncommon with usual doses. CNS: Weakness, muscle cramps, dysphoria, fasciculations, incoordination, dysarthria, dysphagia, convulsions, respiratory paralysis. CV: Bradycardia, irregular pulse, hypotension, pulmonary edema. Special Senses: Miosis, blurred vision, diplopia, lacrimation. GI: Diarrhea, abdominal cramps, nausea, vomiting, excessive salivation. Respiratory: Increased bronchial secretions, bronchospasm, laryngospasm, pulmonary edema. Other: Excessive sweating, urinary frequency, incontinence.
Drug:
Procainamide,
quinidine may antagonize the effects of edrophonium; digitalis glycosides increase the sensitivity of the heart to edrophonium; succinylcholine,
decamethonium may prolong neuromuscular blockade.
Onset: 30–60 sec IV; 2–10 min IM. Duration: 5–10 min IV; 5–30 min IM.
Assessment & Drug Effects
- Monitor vital signs. Observe for signs of respiratory distress. Patients >50 y are particularly likely to develop bradycardia,
hypotension, and cardiac arrest.
- Edrophonium test for myasthenia gravis: All cholinesterase inhibitors (anticholinesterases) should be discontinued for at
least 8 h before test. Positive response to edrophonium test consists of brief improvement in muscle strength unaccompanied
by lingual or skeletal muscle fasciculations.
- Evaluation of myasthenic treatment: Myasthenic response (immediate subjective improvement with increased muscle strength, absence of fasciculations; generally indicates that patient
requires larger dose of anticholinesterase agent or longer-acting drug); Cholinergic response [muscarinic adverse effects (lacrimation, diaphoresis, salivation, abdominal cramps, diarrhea, nausea, vomiting; accompanied
by decrease in muscle strength; usually indicates over-treatment with cholinesterase inhibitor)]; Adequate response [no change in muscle strength; fasciculations may be present or absent; minimal cholinergic adverse effects (observed in
patients at or near optimal dosage level)].
Patient & Family Education
- Do not breast feed while taking this drug without consulting physician.
1%)
Canadian drug name; 
Prototype drug