Myasthenic Syndrome Associated With Antibiotics

ANTIBIOTICS produce weakness by interfering with neuromuscular transmission. Apnea in experimental animals was observed first in 1941 with tyrothricin, the first antibiotic tested for clinical application.¹In 1956, the first case of prolonged apnea in man was reported after intraperitoneally infected neomycin sulfate.²Since 1956, a syndrome characterized by respiratory weakness, flaccid paralysis, and pupillary and visual changes has been recognized in association with a number of antibiotics.³⁻⁵⁰As defined, this "myasthenic syndrome" occurs in patients who do not have myasthenia gravis, although some myasthenics become weaker when given certain antibiotics.⁵¹Recent reviews of antibiotic toxicity do not emphasize this syndrome⁵²⁻⁵⁴Electromyographic (EMG) studies were mentioned in only four patients. In one, neuromuscular transmission and nerve conduction velocities were normal.⁴⁹A "currarelike"³⁰or nondepolarizing³⁴,⁵⁰effect occurred in the others. In one patient⁵⁰the block was not altered by edrophonium chloride. Profound