What is the treatment for myositis?

From the Guidelines

Treatment for myositis typically involves a combination of medications and supportive therapies tailored to the specific type and severity of the condition, with corticosteroids like prednisone being the first-line treatment, starting at 0.5-1 mg/kg/day, and immunosuppressants such as methotrexate, azathioprine, or mycophenolate mofetil being added for patients who don't respond adequately to steroids or need steroid-sparing options 1. The initial drug regimen for adult patients with idiopathic inflammatory myositis should include high-dose corticosteroids concurrent with a steroid-sparing agent, such as methotrexate, azathioprine, or mycophenolate mofetil, followed by a tapering course of corticosteroids 1. For patients with severe myositis, extensive extramuscular organ involvement, or refractory disease, high-dose methylprednisolone in addition to intravenous immunoglobulin, cyclophosphamide, rituximab, or cyclosporine may be used 1. Some key points to consider in the treatment of myositis include:

• The use of magnetic resonance imaging to identify a muscle site for biopsy, diagnose myositis, and monitor treatment response 1
• The importance of physical therapy to maintain muscle strength and prevent contractures, with a program typically including gentle stretching and progressive resistance exercises
• The need for rest during acute flares, but avoiding prolonged inactivity as it can worsen muscle weakness
• The importance of supportive care for any associated conditions, such as dysphagia or interstitial lung disease
• The potential use of novel biomarkers of disease activity, such as interleukin 6 and type 1 interferon-regulated genes, to monitor treatment response 1. In severe or refractory cases, intravenous immunoglobulin (IVIG) at 2 g/kg divided over 2-5 days may be used, and rituximab may be considered as an alternative to cyclophosphamide in patients with refractory disease or severe disease complications 1.

From the FDA Drug Label

Systemic dermatomyositis (polymyositis)

• Treatment for myositis: Prednisone (PO) is indicated for the treatment of systemic dermatomyositis (polymyositis) during an exacerbation or as maintenance therapy in selected cases 2.
• The treatment should be used as adjunctive therapy for short-term administration.

From the Research

Treatment Options for Myositis

• The treatment of myositis typically involves the use of corticosteroids, such as prednisone, often in combination with other immunosuppressive agents like azathioprine or methotrexate 3, 4.
• In cases where patients do not respond to initial treatment, alternative options may include intravenous immunoglobulin, rituximab, mycophenolate mofetil, or tacrolimus 3, 4.
• For patients with inclusion body myositis, a treatment trial with oral prednisone combined with methotrexate may be advised 3.
• Rituximab has been shown to be effective in some patients with myositis, particularly those with positive myositis-specific autoantibodies, with a response rate of 78.3% 5.

Specific Treatment Approaches

• Dermatomyositis and polymyositis are often treated with a combination of prednisone and azathioprine or methotrexate 3, 4.
• In juvenile dermatomyositis, intravenous immunoglobulin has been used as a steroid-sparing agent or as an alternative to cytotoxic treatment, with clinical improvement observed in all nine patients treated in one study 6.
• The choice of treatment should be individualized based on the severity of clinical presentation, disease duration, presence of extramuscular features, and prior therapy and contraindications to particular agents 4.

Challenges in Treatment

• Clinical trials in myositis are rare, making it difficult to establish clear recommendations for treatment 3.
• There is no agreement on the optimal treatment approach for myositis, and treatment guidelines are not well established 4, 7.
• Approximately 25% of patients with myositis do not respond to treatment and may require alternative or experimental therapies 4.