Fusidic Acid: A Neglected Risk Factor for Statin-Associated Myopathy

BACKGROUND: Statins are widely used lipid-lowering drugs used for the prevention of cardiovascular disease. Statins are known to cause myopathy, an adverse drug reaction with various clinical features rhabdomyolysis. OBJECTIVE: To describe clinical characteristics of statin-treated individuals who experienced myopathy and identify risk factors of statin-associated myopathy. METHODS: A retrospective study was conducted on cases of statin-associated myopathy reported to the Swedish Medical Products Agency. Clinical factors were compared between cases and statin-treated controls not diagnosed with myopathy. Statistical methods were univariate and multivariate logistic regression and results were presented as odds ratio (OR) with 95% confidence interval (CI). To correct for multiple comparisons, the cutoff for statistical significance was set to P < .0017. RESULTS: In total, 47 cases of statin-associated myopathy were compared with 3871 treated controls. Rhabdomyolysis was diagnosed in 51% of the cases. Markers for cardiovascular disease were more common in cases than controls. Statistical analysis revealed the following independent risk factors for myopathy: high statin dose (OR = 1.54, calculated using the standard deviation 19.82, 95% CI = 1.32-1.80, P < .0001), and concomitant treatment with fusidic acid (OR = 1002, 95% CI = 54.55-18 410, P < .0001), cyclosporine (OR = 34.10, 95% CI = 4.43-262.45, P = .0007), and gemfibrozil (OR = 12.35, 95% CI = 2.38-64.10, P = .0028). CONCLUSIONS: The risk of myopathy increases with statin dose and cotreatment with cyclosporine and gemfibrozil. Concomitant fusidic acid has previously only been noted in a few case reports. Considering that use of fusidic acid may become more frequent, it is important to remind of this risk factor for statin-associated myopathy.