Edrophonium Chloride

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Cat Number

API0231580

CAS Number

116-38-1

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Product Detail Description Scientific Support Customer Q&A

CAS Number

116-38-1

EINECS

204-138-4

Storage

Store at room temperature

Synonyms

Antirex; Enlon; Reversol; Edrophonii chloridum; Cloruro de edrofonio; Chlorure d'edrophonium; Ethyl(m-hydroxyphenyl)dimethylammonium chloride; N-ethyl-3-hydroxy-N,N-dimethylanilinium chloride

Molecular Formula

C10H16ClNO

Molecular Weight

201.69

Smiles

CC[N+](C)(C)C1=CC(=CC=C1)O.[Cl-]

Appearance

White or almost white crystalline powder

Melting Point

162-163℃

Boiling Point

130℃ (20 mmHg)

Relative Density

1.395

General Description

Edrophonium chloride is a short-acting, reversible acetylcholinesterase inhibitor with a rapid onset (30 to 60 seconds) and brief duration of action (5 to 10 minutes). It is administered intravenously and is chemically classified as a quaternary ammonium compound, limiting its penetration into the central nervous system.

Mechanism of Action

By reversibly binding to the anionic site of the acetylcholinesterase enzyme, edrophonium prevents the hydrolysis of acetylcholine at the neuromuscular junction. This prolongs the presence of acetylcholine in the synaptic cleft, allowing it to compete with non-depolarizing neuromuscular blockers. In myasthenia gravis, the resulting increase in cholinergic transmission temporarily overcomes the autoimmune receptor blockade, improving muscle strength.

Application

Edrophonium was historically used as the "Tensilon test" to diagnose myasthenia gravis, where a brief improvement in muscle strength following administration supported the diagnosis. It has also been employed to distinguish myasthenic crisis from cholinergic crisis. Today, modern diagnostic tools such as antibody testing and electromyography have largely replaced its diagnostic use, though it remains available for selected neuromuscular assessments.

No specific test exists for blepharospasm, which is diagnosed by excluding secondary causes. In a double‑blind study of 10 blepharospasm patients and 10 hemifacial spasm controls, the acetylcholinesterase inhibitor edrophonium markedly worsened both subjective and objective signs of blepharospasm but had no effect on hemifacial spasm. Saline had no effect on either group. The edrophonium challenge test may serve as a useful diagnostic tool to distinguish blepharospasm from other facial movement disorders.

Fig. 1 Mean and SD*1 values of the VAS*2 for the placebo injection session and the edrophonium injection session in patients with blepharospasm. (Matsumoto S, et al., 2016)

References

Matsumoto S, et al. Edrophonium Challenge Test for Blepharospasm. Front Neurosci. 2016;10:226.

Does Edrophonium Chloride require protection from light during long-term storage?

Yes, it is photosensitive. UV light can cause photodegradation and discoloration. Store in light-resistant containers, preferably amber glass.

What is the recommended storage temperature for Edrophonium Chloride?

Store at controlled room temperature (15-25°C). Avoid excessive heat above 30°C, which can accelerate oxidation of the phenolic group.

Is Edrophonium Chloride stable in solution for diagnostic use?

Aqueous solutions are stable for several months when protected from light and stored at room temperature. We provide stability data for various concentrations and preservatives.

How is the impurity m-(dimethylamino)phenol monitored during stability?

This primary degradation product is quantified using a validated HPLC method, ensuring it remains below acceptable limits throughout shelf life.