Intoxication by anticholinesterase compounds may occur in normal subjects after accidental exposure to organophosphorus insecticides (e. g., parathion1and tetraethylpyrophosphate [TEPP]2) and chemical warfare agents (e. g., sarin, one of the "nerve gases," isopropyl methyl phosphonofluoridate3). Similar intoxication may occur as a result of overtreatment of patients with myasthenia gravis with anticholinesterase medication, whether organophosphorus (TEPP or octamethyl pyrophosphoramide [OMPA]) or quaternary ammonium (neostigmine [Prostigmin], bis-neostigmine [BC-40], pyridostigmine [Mestinon], bis-pyridostigmine [hexamarium, BC-51], or ambenomium [Mytelase] ).4These compounds inhibit cholinesterase enzymes throughout the body, resulting in local accumulation of acetylcholine, which produces increased activity of smooth muscle and secretory glands ( manifested by nausea, vomiting, diarrhea, sweating, and increased salivary and bronchial secretion), bradycardia, central nervous system symptoms, muscular weakness, and fasciculations in normal subjects,3and increased strength which may be followed by weakness in patients with myasthenia gravis.4aIn the management of the latter disease,