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 under- 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 marine animals.