IVIG Used as First-Line Monotherapy Attenuates Statin-Triggered Autoimmune Myopathy

Statin-triggered autoimmune myopathy can occur in rare instances where muscle-related symptoms fail to resolve following stoppage of the medication. This condition is characterized by proximal muscle weakness, necrosis of muscle fibers, elevated serum levels of creatine kinase, and the presence of autoantibodies that recognize HMG-CoA reductase, the pharmacologic target of statins.

Among 82 patients with statin-triggered autoimmune myopathy at a single center, three patients with diabetes declined glucocorticoids because of concerns about potential side effects, but agreed to try monotherapy with intravenous immune globulin (IVIG), administered at a dose of 2 g/kg per month. Immediately pre-treatment, the mean creatine kinase level was 4919±3523 IU per liter, and all three patients had documented weakness in the proximal arms and legs. After two or three rounds of IVIG monotherapy, the mean creatine kinase level declined to 1125±1101 IU per liter, mean strength of arm abduction increased from 3.5 to 6.2 kg, and hip-flexion strength improved or normalized.

However, despite partial or full recovery of strength, two patients had persistent creatine kinase elevations, and all three continued to have positive titers for HMG-CoA reductase antibodies. According to the study authors, these findings suggest that IVIG may attenuate statin-treated autoimmune myopathy, allowing muscle regeneration to outpace muscle destruction, but may not completely abolish the pathophysiological processes that cause muscle damage. “Our experience suggests that monotherapy with IVIG may be considered as a first-line treatment for statin-triggered autoimmune myopathy,” they concluded.