Ambenonium is a cholinesterase inhibitor with all the pharmacologic actions of acetylcholine, both the muscarinic and nicotinic types. It was marketed under the brand name Mytelase, but was withdrawn from the market in the United States in 2010. Ambenonium, similar to pyridostigmine and neostigmine, is used for the treatment of muscle weakness and fatigue in people with myasthenia gravis.Ambenonium exerts its actions against myasthenia gravis by competitive, reversible inhibition of acetylcholinesterase. The disease myasthenia gravis occurs when the body inappropriately produces antibodies against acetylcholine receptors, and thus inhibits proper acetylcholine signal transmission (when acetylcholine binds to acetylcholine receptors of striated muscle fibers, it stimulates those fibers to contract). Ambenonium reversibly binds acetylcholinesterase at the anionic site, which results in the blockage of the site of acetycholine binding, thereby inhibiting acetylcholine hydrolysis and enhancing cholinergic function through the accumulation of acetycholine at cholinergic synpases. In turn this facilitates transmission of impulses across the myoneural junction and effectively treats the disease.

Edrophonium is a short and rapid-acting cholinergic drug. Chemically, edrophonium is ethyl (m-hydroxyphenyl) dimethylammonium. Edrophonium is used for the differential diagnosis of myasthenia gravis and as an adjunct in the evaluation of treatment requirements in this disease. It may also be used for evaluating emergency treatment in myasthenic crises. Because of its brief duration of action, it is not recommended for maintenance therapy in myasthenia gravis. It is also useful whenever a curare antagonist is needed to reverse the neuromuscular block produced by curare, tubocurarine, gallamine triethiodide or dimethyl-tubocurarine. It is not effective against decamethonium bromide and succinylcholine chloride. It may be used adjunctively in the treatment of respiratory depression caused by curare overdosage.