Edrophonium anticholinesterase

The pronounced weakness that may result from inadequate therapy of myasthenia gravis (myasthenic crisis) can be distinguished from that due to anticholinesterase overdose (cholinergic crisis) by the use of edrophonium. In cholinergic crisis, edrophonium will briefly cause a further weakening of muscles, whereas improvement in muscle strength is seen in the... 

As given in classification, these agents are of two type e.g. reversible and irreversible. The reversible anticholinesterases have a structural resemblance to acetylcholine, are capable of combining with anionic and esteratic sites of cholinesterase as well as with acetylcholine receptor. The complex formed with the esteratic site of cholinesterase is less readily hydrolyzed than the acetyl esteratic site complex formed with acetylcholine. Edrophonium forms reversible complex with the anionic site and has shorter duration of action. Also, neostigmine and edrophonium have a direct stimulating action at cholinergic sites. 

Drugs acting at this receptor include muscarinic antagonists, such as atropine and anticholinesterases, e.g. neostigmine and edrophonium, which stimulate the receptor indirectly... 

Excessive dosing with an anticholinesterase can actually worsen the muscle weakness in myasthenics if the accumulation of acetylcholine at the neuromuscular junction is sufficient to cause depolarising blockade cholinergic crisis). It is important to distinguish this type of muscle weakness from an exacerbation of the disease itself myasthenic crisis). The dilemma can be resolved with a test dose of edrophonium, which relieves a myasthenic crisis but worsens a cholinergic one. The latter may be severe enough to precipitate respiratory failure and should be attempted only with full resuscitation facilities, including mechanical ventilation, at hand. 

Edrophonium is an anticholinesterase muscle stimulant that facihtates myoneural junction impulse transmission by inhibiting acetylcholine destmction by cholinesterase. It is indicated in differential diagnosis of myasthenia gravis as an adjunct in evaluating treatment of myasthenia gravis in evaluation of aner-gency treatment of myasthenic aises in reversal of neuromuscular blockade by curare gallamine or tubo-curarine and in treatment of respiratory depression caused by curare overdose. 

Following are a few examples of indirectly acting cholinomimetics (anticholinesterase drugs) demecarium bromide edrophonium chloride physostigmine salicylate and pyridostigmine bromide. 

Edrophonium, a competitive anticholinesterase, contains a quaternary ammonium which is attracted to an anionic pocket near the active site of acetylcholinesterase. Edrophonium does not act as long as... 

Several researchers report that administration of the anticholinesterases edrophonium and neostigmine enhance the recovery of motor power and markedly reduce paresthesia and numbness (Chew et al, 1983,1984 Sorokin, 1973 Tan, 1980 Torda et al, 1973). Although these reports are contrary to those of Kao (1966), Chew et al (1983, 1984) suggest that TTX causes a... 

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