Drug-induced neuromuscular blockade and myasthenia gravis.

Myasthenia gravis is an uncommon disorder of the neuromuscular junction resulting in weakness of all striated voluntary muscles. Therapeutic advances have increased patients' age and survival. Older patients with myasthenia gravis may have additional medication needs. Numerous drugs have experimental and clinical evidence of neuromuscular blockade. A MEDLINE search of the English literature from 1966 to the present pertinent to drug-induced myasthenia gravis was performed. Additional literature was obtained from reference citations of relevant articles. Drugs with several reports of neuromuscular blockade were assessed for causality by a recognized probability scale. Prednisone was most commonly implicated as aggravating myasthenia gravis, and D-penicillamine was most commonly associated with myasthenic syndrome. The greatest frequency of drug-induced neuromuscular blockade was seen with aminoglycoside-induced postoperative respiratory depression. However, drugs most likely to impact myasthenic patients negatively are those used in the treatment of the disease. These include overuse of anticholinesterase drugs, high-dose prednisone, and anesthesia and neuromuscular blockers for thymectomy.