Toxic Myopathies

Many exogenous substances, mainly prescribed drugs, can cause myopathic adverse effects. Immune checkpoint inhibitors cause an inflammatory myopathy relatively frequently. An immune-mediated myopathy can be exceedingly rarely caused by statins. Weakness in these myopathies can be severe and these disorders need to be treated promptly with immune-suppressive and immune-modulating medication. Statins have also a direct effect on muscle and very rarely cause a necrotizing myopathy, which resolves with discontinuation of the drug. Muscle discomfort with normal CK and muscle strength is in general no adverse effect of statins. Hydroxy)chloroquine, colchicine and amiodarone can cause a reversible vacuolar myopathy. High-dose glucocorticoids and chronic alcohol abuse cause muscle wasting.