Drug-related myopathies.

Myopathies produced by drugs are of vital concern and often confused with other more frequently diagnosed causes, such as the inflammatory myopathies of polymyositis/dermatomyositis and myositis secondary to toxic agents, metabolic and endocrine abnormalities, genetic predisposition, malignancies, and infections, particularly viruses. The drug-induced causes of myopathy warrant special emphasis because they are often overlooked, resulting in misdiagnosis and improper care.