Toxic myopathies: muscle biopsy features

several drugs and toxic substances can cause muscular abnormalities and are frequent causes of acquired myopathies. we present a series of 32 patients, predominance of young adult patients, diagnosed with toxic myopathy. the most common substances inducing myopathy were corticosteroids (56.2%) followed by the propoxyphene, neuroleptics, zidovudine and drug-induced hypokalemia. the investigation showed normal serum creatine kinase levels in 65.4%, myopathic pattern of the needle electromyography in 40% and the more frequent histological diagnosis of the muscle biopsy was type 2 fiber atrophy (59.3%). clinical features, etiology, course of the disease, serum levels of muscular enzymes, electromyographic features and, especially, muscle biopsy features are discussed.