Glucocorticoid-induced myopathy.

Glucocorticoid-induced myopathy, characterized by muscle weakness without pain, fatigue and atrophy, is an adverse effect of glucocorticoid use and is the most common type of drug-induced myopathy. This muscle disturbance has a frequency of 60%, and it has been most often associated with fluorinated glucocorticoid preparations. Glucocorticoids have a direct catabolic effect on muscle, decreasing protein synthesis and increasing the rate of protein catabolism leading to muscle atrophy. In clinical practice, it is important to differentiate myopathy due to glucocorticoid from muscle inflammatory diseases. The treatment is based on reduction or, if possible, on discontinuation of the steroid. Fluorinated glucocorticoids such as dexamethasone should be replaced with nonfluorinated glucocorticoids such as prednisone. Other experimental treatments may be tried such as IGF-I, branched-chain amino acids, creatine, androgens such as testosterone, nandrolone and dehydroepiandrosterone (DHEA), and glutamine.