Edrophonium

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, Enlon and Reversol.

Clinical uses
Because its duration of action is only about 10 minutes, edrophonium (by the so-called Tensilon test) is used to differentiate myasthenic crisis from cholinergic crisis. In myasthenic crisis, where a person is not able to produce enough neuromuscular stimulation, edrophonium will reduce the muscle weakness by effectively supplying more acetylcholine. In a cholinergic crisis, where a person has too much neuromuscular stimulation, edrophonium will make the muscle weakness worse by inducing a depolarizing block.