Prednisone-induced worsening of neuromuscular function in myasthenia gravis.

In patients with myasthenia gravis who received single doses of prednisone orally (40 to 100 mg), we found acute inhibition of neuromuscular function as manifest by increased decremental responses to repetitive nerve stimulation, reduced twitch tension, and lowered maximum voluntary contraction strength. The time course of these changes correlated with plasma methylprednisolone levels, implying direct drug effects on neuromuscular function.