Edrophonium chloride

Chemical properties

White or almost white, crystalline powder

Originator

Tensilon,Roche,US,1951

The Uses of Edrophonium chloride

A reversible Acetylcholinesterase inhibitor.

The Uses of Edrophonium chloride

Myasthenia Gravis test;Cholinergic

The Uses of Edrophonium chloride

Edrophonium (chloride) is an acetylcholinesterase (AChE) inhibitor that is known to prevent the breakdown of the neurotransmitter acetylcholine by binding specifically to its catalytic site. It has been shown to inhibit AChE activity in human red blood cells, purified calf forebrain, and purified octopus brain with Ki values of 0.2, 0.2, and 0.4 μM, respectively. Edrophonium is often used as part of a battery of pharmacological tests to confirm a diagnosis of the autoimmune neuromuscular junction disorder, myasthenia gravis.

The Uses of Edrophonium chloride

Pharmacologically, edrophonium is also similar to neostigmine; however, it begins to act quicker and is shorter lasting.

Definition

ChEBI: The chloride salt of edrophonium. A reversible inhibitor of cholinesterase with a rapid onset (30-60 seconds after injection) but a short duration of action (5-15 minutes), it is used in myasthenia gravis both diagnostically and to distinguish between unde - or over-treatment with other anticholinesterases. It has also been used for the reversal of neuromuscular blockade in anaesthesia, and for the management of poisoning due to tetrodotoxin, a neuromuscular blocking toxin found in puffer fish and other mari e animals.

Manufacturing Process

A solution made up of 10 grams of m-dimethylaminophenol, 50 cc of acetone and 13 grams of ethyl iodide was heated at 50°C for five hours. On addition of ether to the cooled solution, (3-hydroxyphenyl)ethyl dimethylammonium iodide precipitated as an oil which soon crystallized. Upon recrystallization from isopropanol the compound had a MP of 113° to 115°C.
A slight excess of a 10% sodium hydroxide solution was added to a solution of 23 grams of silver nitrate in 300 cc of water. The precipitated silver oxide was washed free of silver ion with distilled water. To a suspension of the silver oxide in 200 cc of water, a solution of 25 grams of (3-hydroxyphenyl)ethyl dimethylammonium iodide in 300 cc of water was added. The precipitate of silver iodide was removed by filtration and the filtrate concentrated to a volume of about 100 cc in vacuo. The remainder of the water was removed by lyophilization. (3-hydroxyphenyl)ethyl dimethylammonium hydroxide was obtained as a hygroscopic, amorphous solid.
A solution of 5 grams of (3-hydroxyphenyl)ethyl dimethylammonium hydroxide in about 200 cc of water was neutralized with dilute hydrochloric acid. On concentration to dry ness in vacuo, (3-hydroxyphenyl)ethyl dimethylammonium chloride crystallized. The compound was recrystallizedfrom isopropanol; MP 162° to 163°C (with decomposition).

brand name

Enlon (Baxter Healthcare); Reversol (Organon); Tensilon (Valeant).

Therapeutic Function

Cholinergic (ophthalmic)

General Description

Edrophonium chloride,ethyl(m-hydroxyphenyl)dimethylammonium chloride(Tensilon), is a reversible anticholinesterase agent. It isbitter and very soluble in water and alcohol. Edrophoniumchloride injection has a pH of 5.2 to 5.5. On parenteral administration,edrophonium has a more rapid onset andshorter duration of action than neostigmine, pyridostigmine,or ambenonium. It is a specific anticurare agent andacts within 1 minute to alleviate overdose of d-tubocurarine,dimethyl d-tubocurarine, or gallamine triethiodide.

Biological Activity

edrophonium is a competitive inhibitor of acetylcholinesterase (ache) [1]. ache is an extrinsic membrane-hound enzyme that functions in the central and peripheral nervous systems. ache rapidly terminates the ach receptor-mediated signal transmission by hydrolyzing ach. inhibition of ache results in accumulation of ach in the synaptic cleft and leads to impeded neurotransmission [2].

Clinical Use

Edrophonium Chloride is also used to terminate the action of any one ofthese drugs when the physician so desires. It is of no value,however, in terminating the action of the depolarizing (i.e.,noncompetitive) blocking agents, such as decamethoniumand succinylcholine. In addition to inhibiting AChE, edrophoniumchloride has a direct cholinomimetic effect onskeletal muscle, which is greater than that of most otheranticholinesterase drugs.

Synthesis

Edrophonium, ethyl-(3-hydroxyphenyl)dimethylammonium chloride (13.2.13), is made by reacting 3-dimethylaminophenol with ethylbromide, which forms ethyl(3-hydroxyphenyl)dimethylammonium bromide (13.2.12), the bromine atom of which is replaced with a chlorine atom by reacting it with silver chloride, giving edrophonium (13.2.13) [45].

Veterinary Drugs and Treatments

The primary use for edrophonium is in the diagnosis of myasthenia gravis. It can also be used for the reversal of nondepolarizing agents (e.g., vecuronium, pancuronium, metocurine, atracurium, gallamine or tubocurarine). Because of its short duration of action, its clinical usefulness for this indication is questionable as longer acting drugs such as neostigmine or pyridostigmine may be more useful. Edrophonium, in a controlled intensive care-type setting, may also be useful in the diagnosis and treatment of some supraventricular arrhythmias, particularly when other more traditional treatments are ineffective.

in vitro

edrophonium inhibited ache activity in human red blood cells, purified calf forebrain, and octopus brain with ki values of 0.2, 0.2, and 0.4 μm, respectively. the ic50s were 0.2, 0.05, and 0.5 μm, respectively [1].

in vivo

in symptomatic patients without coronary artery disease, edrophonium (80 μg/kg, intravenous bolus) induced chest pain [3]. edrophonium increased esophageal amplitude and repetitive contractions. edrophonium was useful for provoking esophageal chest pain [3]. in infants and children during n2o-halothane anesthesia, the ed50 for edrophonium is 128 μg/kg for adults [4]. in patients anaesthetized with nitrous oxide and halothane undergoing kidney transplant nephrectomy or transplantation of a live related donor kidney, patients undergoing transplant nephrectomy showed a significant increase in elimination half-life and a significant decrease (67%) in serum clearance when compared with kidney transplant recipients or patients with normal renal function [5].

References

[1] boyle n a j, talesa v, giovannini e, et al. synthesis and study of thiocarbonate derivatives of choline as potential inhibitors of acetylcholinesterase[j]. journal of medicinal chemistry, 1997, 40(19): 3009-3013.
[2] quinn d m. acetylcholinesterase: enzyme structure, reaction dynamics, and virtual transition states[j]. chemical reviews, 1987, 87(5): 955-979.
[3] cronnelly r, morris r b, miller r d. edrophonium: duration of action and atropine requirement in humans during halothane anesthesia[j]. anesthesiology, 1982, 57(4): 261-266.
[4] fisher d m, cronnelly r, sharma m, et al. clinical pharmacology of edrophonium in infants and children[j]. anesthesiology, 1984, 61(4): 428-433.
[5] morris r b, cronnelly r, miller r d, et al. pharmacokinetics of edrophonium in anephric and renal transplant patients[j]. british journal of anaesthesia, 1981, 53(12): 1311-1314.