edrophonium test, a test for myasthenia gravis in which an IV solution of edrophonium chloride is injected into a patient. A total of 10 mg of the cholinergic drug is prepared, and a 2-mg dose is injected. If there is no reaction in 30 seconds, the remaining 8 mg is administered. A brief improvement in muscle activity is regarded as a positive result. Edrophonium chloride is also used to distinguish between myasthenia gravis and a cholinergic crisis. Because edrophonium chloride can precipitate respiratory depression, the test should not be performed unless an anticholinergic antidote, such as atropine, and respiratory resuscitation equipment are available.
