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Statin-Induced Myopathy

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Statin-Induced Myopathy, Rhabdomyolysis due to Statin, Statin-Induced Myalgias, Myositis due to Statins, Statin Myopathy

  • See Also
  • Epidemiology
  • Mechanism
  1. Typical Myopathy
    1. Muscle injury secondary to Statin use (drug-induced Myopathy - accelerating muscle cell death)
  2. Statin-Induced Immune-mediated Necrotizing Myopathy
    1. Newly defined in 2011
    2. Symptoms and findings (including CPK) remain abnormal after stopping the Statin
  • Symptoms
  1. Myalgia
    1. Muscle ache or weakness with normal CPK
  2. Myostitis
    1. Muscle ache or weakness with CPK elevated but <10 fold increase above normal
  3. Rhabdomyolysis
    1. Muscle ache or weakness with CPK elevated but >10 fold increase above normal
  • Symptoms
  • Red Flags
  1. Patient should stop Statin and contact physician if following symptoms experienced
  2. Severe myalgias
  3. Muscle Weakness
  4. Dark Urine
  • Labs
  1. Creatine Phosphokinase (CPK)
    1. Poor marker for myalgias (only increased in Myositis or Rhabdomyolysis)
    2. Normal in most patients despite myalgias
    3. Abnormal CPK suggests Myositis or Rhabdomyolysis and requires immediate cessation of Statin
  2. Additional labs in CPK Elevation (especially Rhabdomyolysis)
    1. Urine Myoglobin
    2. Renal Function
  3. Labs to consider in differential diagnosis
    1. Vitamin D Level
    2. Thyroid Stimulating Hormone (TSH)
  1. Statin combination with Gemfibrozil (and to a lesser extent with Fenofibrate)
  2. Drug Interactions (see Statins)
    1. Raised serum Statin levels result in higher myalgia or Myositis risk
  3. Older patients over age 70 years
  4. Low body weight
  5. Female gender
  6. Acute illness or major surgery
  7. Alcohol Abuse or other Substance Abuse (e.g. Cocaine, Amphetamines)
  8. Hypothyroidism
  9. Chronic Kidney Disease Stage 4 (Creatinine Clearance <30 ml/min)
  10. High dose Statin use (dose greater than 50% of maximum dose, especially Simvastatin 80 mg)
  • Management
  • Symptomatic
  1. Coenzyme Q10 (Ubiquinone) 100 mg orally daily
    1. Reduces myalgias by 40% in one study (other studies show no efficacy)
    2. Caso (2007) Am J Cardiol 99:1409-12 [PubMed]
  2. Decrease Statin dose by 50%
  3. Consider alternate day dosing or twice weekly dosing
  4. Consider Ezetimibe as an adjunct to allow lowering Statin dose
  5. Consider change to alternative Statin
    1. Initially thought that hydrophilic Statins (Pravastatin, Rosuvastatin) were less likely to cause myalgias
    2. Hydrophilic Statins do not appear to offer any increased benefit over other Statins regarding myalgia risk
      1. Thompson (2003) JAMA 289(13): 1681-90 [PubMed]