Edrophonium

Edrophonium
Systematic (IUPAC) name
N-Ethyl-3-hydroxy-N,N-dimethylbenzenaminium
Clinical data
Trade names Tensilon
AHFS/Drugs.com FDA Professional Drug Information
Identifiers
CAS Number 116-38-1 YesY
ATC code none
PubChem CID 8307
DrugBank DB01010 YesY
ChemSpider 8006 YesY
UNII QO611KSM5P YesY
KEGG D00994 YesY
ChEBI CHEBI:4759 YesY
ChEMBL CHEMBL1128 YesY
Chemical data
Formula C10H16NO+
Molar mass 166.24 g/mol
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Edrophonium is a readily reversible acetylcholinesterase inhibitor. It prevents breakdown of the neurotransmitter acetylcholine and acts by competitively inhibiting the enzyme acetylcholinesterase, mainly at the neuromuscular junction. It is sold under the trade names Tensilon and Enlon (according to FDA Orange Book).

Clinical uses

Edrophonium (by the so-called Tensilon test) is used to differentiate myasthenia gravis from cholinergic crisis and Lambert-Eaton myasthenic syndrome. In myasthenia gravis, the body produces autoantibodies which block, inhibit or destroy nicotinic acetylcholine receptors in the neuromuscular junction. Edrophonium—an effective acetylcholinesterase inhibitor—will reduce the muscle weakness by blocking the enzymatic effect of acetylcholinesterase enzymes, prolonging the presence of acetylcholine in the synaptic cleft. It binds to a Serine-103 allosteric site, while pyridostigmine and neostigmine bind to the AchE active site for their inhibitory effects. In a cholinergic crisis, where a person has too much neuromuscular stimulation, edrophonium will make the muscle weakness worse by inducing a depolarizing block.

Lambert-Eaton myasthenic syndrome (LEMS), is similar to myasthenia gravis in that it is an autoimmune disease. However, in LEMS the neuron is unable to release enough acetylcholine for normal muscle function due to autoantibodies attacking P/Q-type calcium channel that are necessary for acetylcholine release. This means there is insufficient calcium ion influx into presynaptic terminal resulting in reduced exocytosis of acetylcholine containing vesicles. Consequently, there will typically be not as much increase in muscle strength observed after edrophonium injection, if any with LEMS.

The drug may also be used for postoperative decurarization.[1]

Chemistry

Edrophonium, ethyl-(3-hydroxyphenyl)dimethylammonium chloride, is made by reacting 3-dimethylaminophenol with ethyl bromide, which forms ethyl(3-hydroxyphenyl)dimethylammonium bromide, the bromine atom of which is replaced with a chlorine atom by reacting it with silver chloride, giving edrophonium.

Pharmacokinetics

The drug has a brief duration of action, about 10–30 mins.[1]

Sources

  1. Brenner, G. M. (2000). Pharmacology. Philadelphia, PA: W. B. Saunders Company. ISBN 0-7216-7757-6
  2. Canadian Pharmacists Association (2000). Compendium of Pharmaceuticals and Specialties (25th ed.). Toronto, ON: Webcom. ISBN 0-919115-76-4

Reference

  1. 1 2 KD Tripati MD. Essentials of Medical Pharmacology (fifth ed.). Jaypee Brothers Medical Publishers(P) Ltd. p. 84. ISBN 81-8061-187-6.
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