From the Guidelines
Statin myopathy typically presents as muscle pain, tenderness, or weakness, often affecting large muscle groups like the thighs, shoulders, and back, and can develop at any time during treatment, though it commonly appears within the first few weeks to months after starting therapy or increasing the dose, as recommended by the 2013 ACC/AHA guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults 1.
Signs and Symptoms
The signs of statin myopathy include:
- Muscle pain, tenderness, or weakness
- Muscle cramps, stiffness, fatigue
- In rare severe cases, rhabdomyolysis (characterized by dark urine, severe muscle pain, and kidney problems) These symptoms can range from mild discomfort to severe pain that interferes with daily activities.
Risk Factors
Risk factors for statin myopathy include:
- Higher statin doses
- Advanced age
- Female gender
- Small body frame
- Kidney or liver disease
- Hypothyroidism
- Vitamin D deficiency
- Certain medications that interact with statins (like fibrates, macrolide antibiotics, and some antifungals)
Diagnosis and Management
According to the guideline, baseline measurement of CK is reasonable for individuals believed to be at increased risk for adverse muscle events because of a personal or family history of statin intolerance or muscle disease, clinical presentation, or concomitant drug therapy that might increase the risk of myopathy 1. Additionally, during statin therapy, it is reasonable to measure CK in individuals with muscle symptoms, including pain, tenderness, stiffness, cramping, weakness, or generalized fatigue 1. If you suspect statin myopathy, consult your healthcare provider before stopping medication, as they may recommend checking creatine kinase levels, adjusting your dose, trying a different statin, or implementing alternative cholesterol management strategies.
From the FDA Drug Label
Risk factors for myopathy include age 65 years or greater, uncontrolled hypothyroidism, renal impairment, concomitant use with certain other drugs (including other lipid-lowering therapies), and higher simvastatin dosage; The risk of myopathy is increased by elevated plasma levels of simvastatin and simvastatin acid. Instruct patients to promptly report any unexplained muscle pain, tenderness or weakness, particularly if accompanied by malaise or fever.
Signs of statin myopathy include:
- Unexplained muscle pain
- Tenderness
- Weakness
- Malaise
- Fever
When it starts: The text does not specify exactly when statin myopathy starts, but it can occur at any time during treatment with simvastatin or atorvastatin. It is recommended to inform patients of the risk of myopathy and rhabdomyolysis when starting or increasing the simvastatin or atorvastatin dosage 2, 2, 3.
From the Research
Signs of Statin Myopathy
- Statin-associated muscle symptoms can affect 10% to 15% of statin users 4, 5
- Statin myopathy includes a wide spectrum of clinical conditions, ranging from mild myalgia to rhabdomyolysis 4
- Symptoms can range from asymptomatic creatine kinase (CK) elevation, to muscle pain, weakness, and its most severe form, rhabdomyolysis 5
Onset of Statin Myopathy
- The exact timing of when statin myopathy starts is not specified in the provided studies
- However, it is mentioned that certain patient and drug characteristics increase the risk for statin myopathy, including higher statin doses, statin cytochrome metabolism, and polypharmacy 4
- Genetic risk factors, such as a single nucleotide polymorphism of SLCO1B1, can also increase the risk of statin myopathy 4
Risk Factors for Statin Myopathy
- Higher risk patients for statin myopathy are those older than 80, with a small body frame, on higher statin doses, on other medications, or with other systemic diseases including hepatic or renal diseases, diabetes mellitus, or hypothyroidism 5
- Certain medications and conditions, such as polypharmacy and genetic predispositions, can also increase the risk of statin myopathy 4, 5
Management of Statin Myopathy
- Coenzyme Q10 and vitamin D have been used to prevent and treat statin myopathy, but clinical trial evidence demonstrating their efficacy is limited 4, 6, 7
- Statin-intolerant patients may be successfully treated with either low-dose statins, alternate-day dosing, or using twice-weekly dosing with longer half-life statins 4
- Exchange of statin may be beneficial, and reduction of dose is worth trying, especially in primary prevention 8