From the Guidelines
Inflammatory myositis should be treated with high-dose corticosteroids, usually prednisone at 0.5-1 mg/kg/day, concurrent with a steroid-sparing agent, such as methotrexate, azathioprine, or mycophenolate mofetil, as the initial drug regimen, followed by a tapering course of corticosteroids, as recommended by the most recent and highest quality study 1.
Diagnosis and Treatment
Inflammatory myositis is a group of autoimmune disorders characterized by muscle inflammation, leading to weakness and pain. The diagnosis is based on clinical features, muscle biopsy, and the presence of myositis-specific autoantibodies. Treatment typically begins with high-dose corticosteroids, which should be continued until symptoms improve and creatine kinase levels normalize, usually over 4-6 weeks.
Initial Treatment Regimen
- High-dose corticosteroids, usually prednisone at 0.5-1 mg/kg/day (typically 40-60 mg daily)
- Concurrent with a steroid-sparing agent, such as methotrexate, azathioprine, or mycophenolate mofetil
Steroid-Resistant Cases
For steroid-resistant cases or to reduce steroid dependence, immunosuppressants like methotrexate (15-25 mg weekly), azathioprine (1-2 mg/kg/day), or mycophenolate mofetil (1-1.5 g twice daily) are added.
Severe or Refractory Cases
In severe or refractory cases, intravenous immunoglobulin (2 g/kg divided over 2-5 days) or rituximab (two 1 g infusions separated by two weeks) may be necessary.
Monitoring and Maintenance
Regular monitoring of muscle enzymes, particularly creatine kinase, helps assess disease activity and treatment response. Physical therapy is essential throughout treatment to maintain muscle strength and prevent contractures. Patients should be monitored for medication side effects, including infection risk, and receive appropriate vaccinations before starting immunosuppressive therapy.
Recent Guidelines
Recent guidelines, such as those from the Journal of Clinical Oncology 1 and the Annals of the Rheumatic Diseases 1, emphasize the importance of prompt recognition and early management of myositis, and provide recommendations for the use of high-dose systemic glucocorticoids, intravenous immunoglobulins, and plasma exchanges in severe cases.
Key Considerations
- Myositis can be a severe condition, and prompt recognition and early management are crucial.
- High-dose systemic glucocorticoids are the first-line treatment.
- Intravenous immunoglobulins and plasma exchanges may be necessary in severe cases.
- Regular monitoring of muscle enzymes and physical therapy are essential throughout treatment.
From the FDA Drug Label
- Collagen Diseases During an exacerbation or as maintenance therapy in selected cases of: Systemic lupus erythematosus Systemic dermatomyositis (polymyositis)
- The diagnosis of inflammatory myositis is Systemic dermatomyositis (polymyositis).
- The treatment for inflammatory myositis is prednisone, which can be used as adjunctive therapy for short-term administration or as maintenance therapy in selected cases. 2
From the Research
Diagnosis and Treatment of Inflammatory Myositis
- Inflammatory myositis is a heterogeneous group of diseases including dermatomyositis, polymyositis, and inclusion body myositis 3.
- The treatment of inflammatory myositis remains largely empirical, with corticosteroids being the first-line therapy 4.
- Corticosteroids, such as prednisolone and methylprednisolone, are used as first-line therapy for idiopathic inflammatory myopathy (IIM) 5.
- Immunosuppressive agents, such as azathioprine, methotrexate, or tacrolimus, are used as second-line therapy when symptoms cannot be sufficiently improved with corticosteroids alone 5, 6.
- Intravenous immunoglobulin is recommended for severe cases of IIM, and can be used as add-on therapy in patients not adequately controlled with steroids or immunosuppressive agents 5, 6, 4, 7.
- Biologics, such as rituximab, can be introduced if other therapies do not improve symptoms 5.
- Physiotherapy is effective in improving muscle strength, endurance, and maintaining joint motion in patients with myositis 6.
- Treatment strategies may vary depending on the specific type of inflammatory myositis, with dermatomyositis and polymyositis often requiring a combination of corticosteroids and immunosuppressive agents 3, 6, 7.
- Inclusion body myositis may require a trial of prednisolone and methotrexate, especially in cases with elevated serum creatine kinase (CK) or an inflammatory infiltrate in the muscle biopsy 6, 7.