eMedicine Specialties > Rheumatology > Systemic Rheumatic Disease
Polymyositis: Treatment & Medication
Updated: Nov 6, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Treatment
Medical Care
Treatment of polymyositis (PM) is empirical because of the rarity of the disease and the paucity of randomized controlled trials.
- Prednisone is the first-line treatment of choice for polymyositis.
- Typically, the dose is 1 mg/kg/d, either as a single or divided dose. This high dose is usually continued for 4-8 weeks, until the CK level returns to reference ranges. Taper prednisone by 5-10 mg on a monthly basis until the lowest dose that controls the disease is reached.
- Monitor response to therapy based on improvement in muscle strength and muscle endurance and decrease in CK levels.
- Closely monitor patients with polymyositis for disease activity and adverse effects of corticosteroids such as weight gain, hypertension, osteopenia, and steroid myopathy.
- Corticosteroid myopathy can occur during the course of treatment and must be distinguished from reactivation of muscle disease. CK level is usually within reference ranges in patients with steroid myopathy. No improvement is observed with raised doses of steroids, and the condition worsens if the dose is increased.
- Immunosuppressive agents are indicated in patients who do not improve with steroids within a reasonable period (ie, 4 wk) or if adverse effects from corticosteroids develop. Patients with poor prognostic indicators, such as dysphagia or dysphonia, are likely to require immunosuppressive agents. Under these circumstances, methotrexate is the second-line agent. Patients with inclusion body myositis usually respond poorly to corticosteroids and immunosuppressive agents.
- Obtain baseline liver function tests and pulmonary functions before initiating therapy.
- Azathioprine, cyclophosphamide, chlorambucil, and cyclosporine have been used with varying success as second-line agents for polymyositis.
- Intravenous immunoglobulin (IVIG) has been used for the short-term treatment of steroid-resistant cases of polymyositis.3,4
- The role of newer agents, such as TNF inhibitors, remains unclear. However, the use of TNF inhibitors in refractory cases has demonstrated some success.5
- Recently, an open-label study of patients with dermatomyositis treated with rituximab (anti-CD20 monoclonal antibody) provided encouraging results.6 This may be a new approach to therapy for refractory cases.
- A study is currently under way to evaluate the safety of interferon alfa-2a in adult patients with dermatomyositis or polymyositis.
- A study to evaluate the effectiveness of an anti-C5 (complement) in the treatment of dermatomyositis was recently completed at the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS).
- Extramuscular manifestations of polymyositis are treated as follows:
- Constitutional symptoms of polymyositis, such as fever and fatigue, usually respond to corticosteroids.
- Articular symptoms of polymyositis usually resolve with treatment of the myositis. Some patients develop a rheumatoidlike arthropathy, which may require immunosuppressive treatment such as methotrexate.
- Patients with severe interstitial lung disease may benefit from high-dose steroids and immunosuppressive treatment, especially cyclophosphamide.
- Cardiac abnormalities may respond to corticosteroids. Symptomatic arrhythmias require antiarrhythmic therapy, and symptomatic heart block is treated with placement of a pacemaker.
- Dysphagia responds either slowly or poorly to immunosuppressive therapies and may be severe enough to require enteral feeding through a gastrostomy tube or parenteral nutrition.
Consultations
- Rheumatologists
- Neurologists
- Pulmonary specialists
- Cardiologists
- Physical therapists
- Speech therapists (for swallow evaluation)
Diet
- Patients with polymyositis may benefit from a high-protein diet. Histamine 2 receptor antagonists, proton pump inhibitors, and/or prokinetic agents may be useful in patients with esophageal reflux and dysmotility.
- Monitor patients to avoid excessive weight gain due to corticosteroid use.
- Prescribe calcium with vitamin D supplementation and oral bisphosphonates for osteoporosis prophylaxis.
Activity
- Encourage patients with polymyositis to start a supervised exercise program early in the disease course.7
- During the acute stage of polymyositis, patients may benefit from heat therapy, passive range-of-motion exercises, and splints to avoid contractures.
- Once acute inflammation is under control, the rehabilitation program should include active range-of-motion exercises and isometric contractions of the muscle groups.
- With improvement in muscle strength, patients should perform isotonic exercises with light resistance.
- Encourage patients to do 15-30 minutes of aerobic exercise when the disease is inactive.
Medication
The goals of pharmacotherapy are to reduce morbidity and to prevent complications.
Corticosteroids
These agents inhibit the inflammatory process via multiple mechanisms, including inhibiting proinflammatory cytokine production, monocyte/macrophage function, and angiogenesis.
Prednisone (Sterapred)
Anti-inflammatory and immunosuppressive agent used in the treatment of autoimmune disorders; may decrease inflammation by reversing increased capillary permeability and suppressing neutrophilic activity. Also stabilizes lysosomal membrane and suppresses lymphocytes, reducing cytokine and antibody production.
Adult
1 mg/kg/d PO for 4-8 wk until CK findings return to normal limits; initially administered in divided doses; taper gradually to maintain control of disease activity
Pediatric
0.5-2 mg/kg/d PO for 4-8 wk until CK findings return to normal limits; initially administered in divided doses; taper gradually to maintain control of disease activity
Coadministration with estrogens may decrease clearance; concurrent use with digoxin may cause digitalis toxicity secondary to hypokalemia; phenobarbital, phenytoin, and rifampin may increase metabolism of corticosteroids (consider increasing maintenance dose); monitor for hypokalemia with coadministration of diuretics
No absolute contraindication; severe bacterial, viral, or fungal infections; active peptic ulcer disease; diabetes mellitus
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Abrupt discontinuation of corticosteroids may cause adrenal crisis; hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, growth suppression, and infections may occur with corticosteroid use
Immunosuppressants
These agents may be of benefit in patients whose conditions have not responded to steroids or in patients unable to tolerate prednisone.
Methotrexate (Rheumatrex, Folex PFS)
Unknown mechanism of action in treatment of chronic inflammatory diseases; may affect immune function, including inhibition of production of proinflammatory cytokines. Ameliorates symptoms of inflammation (eg, pain, swelling, stiffness). Adjust dose gradually to attain satisfactory response.
Adult
7.5 mg/wk PO/SC given as single dose; increase weekly dose by 2.5-5 mg, depending on clinical response and toxicity; not to exceed a dose of 25 mg/wk; may also be administered IV
Pediatric
0.25 mg/kg/wk PO/SC given as a single dose; increase weekly dose to a maximum of 0.6 mg/kg/wk, depending on clinical response and toxicity
Oral aminoglycosides may decrease absorption and blood levels of concurrent oral MTX; charcoal lowers levels; administration with etretinate may increase hepatotoxicity; administration of NSAIDs (eg, indomethacin, phenylbutazone) can increase plasma levels; may decrease phenytoin serum levels; probenecid, salicylates, procarbazine, and sulfonamides, including TMP-SMZ, may increase effects and toxicity; may increase plasma levels of thiopurines
Documented hypersensitivity; alcoholism; hepatic insufficiency; documented immunodeficiency syndromes; preexisting blood dyscrasias (eg, bone marrow hypoplasia, leukopenia, thrombocytopenia, significant anemia); renal insufficiency
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Monitor CBC counts monthly and liver and renal function q1-3mo during therapy (monitor more frequently during initial dosing, dose adjustments, or risk of elevated levels [dehydration]; has toxic effects on hematologic, renal, GI, pulmonary, and neurologic systems; discontinue with significant drop in blood counts; aspirin, NSAIDs, or low-dose steroids may be administered concomitantly; (possibility of increased toxicity with NSAIDs, including salicylates, has not been tested); folic acid 1 mg/d decreases the incidence of mucositis and other adverse GI effects
Azathioprine (Imuran)
Purine analog that inhibits synthesis of DNA, RNA, and proteins. May decrease proliferation of immune cells, which results in lower immunological activity.
Adult
Starting dose of 1 mg/kg/d PO for 4-8 wk; increase by 0.5 mg/kg qmo, depending on clinical and hematologic response and toxicity up to 2.5-3 mg/kg/d
Pediatric
Starting dose of 0.5-1 mg/kg/d PO for 4-8 wk; increase by 0.5 mg/kg qmo, depending on clinical and hematologic response and toxicity up to 2.5-3 mg/kg/d
Toxicity increases with allopurinol; concurrent use with ACE inhibitors may induce severe leukopenia; may increase levels of MTX metabolites; decreases the effects of anticoagulants, neuromuscular blockers, and cyclosporine
Documented hypersensitivity; low levels of serum TPMT; active infection; severe cytopenias
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Nausea and vomiting, leukopenia, thrombocytopenia, anemia, infection, abnormal LFTs may occur, rarely, pancreatitis
Immune globulin, intravenous (Sandoglobulin, Gamimune, Gammagard)
Neutralizes circulating myelin antibodies through anti-idiotypic antibodies; down-regulates proinflammatory cytokines, including IFN-gamma; blocks Fc receptors on macrophages; suppresses helper T and B lymphocytes and augments suppressor T lymphocytes. Exact mechanism of action in treatment of polymyositis is unknown.
Adult
1-2 g/kg IV over 2 d, given qmo for 6 mo
Pediatric
Administer as in adults
Increases toxicity of live virus vaccine (MMR); do not administer within 3 mo of vaccine
Documented hypersensitivity; IgA deficiency; anti-IgE/IgG antibodies
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Check serum IgA before IVIG (use an IgA-depleted product, eg, Gammagard S/D); infusions may increase serum viscosity and thromboembolic events; infusions may increase risk of migraine attacks, aseptic meningitis (10%), urticaria, pruritus, or petechiae (2-5 d postinfusion to 30 d); increases risk of renal tubular necrosis in elderly patients and in patients with diabetes, volume depletion, and preexisting kidney disease; lab result changes associated with infusions include elevated antiviral or antibacterial antibody titers for 1 mo, 6-fold increase in ESR for 2-3 wk, and apparent hyponatremia
Chlorambucil (Leukeran)
Alkylates and cross-links strands of DNA, inhibiting DNA replication and RNA transcription.
Adult
0.1-0.2 mg/kg/d PO; average maintenance dose is 2-4 mg/d
Pediatric
Administer as in adults
None reported
Documented hypersensitivity; active infection; depressed bone marrow function
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Caution with history of seizure disorder or with bone marrow suppression; increased risk of hematologic malignancy
Cyclophosphamide (Cytoxan, Neosar)
Chemically related to nitrogen mustards. As an alkylating agent, the mechanism of action of the active metabolites may involve cross-linking of DNA, which may interfere with growth of normal cells such as lymphocytes and neoplastic cells.
Adult
1-3 mg/kg/d PO; may be given as pulse therapy at 500-1000 mg/m2/mo IV
Pediatric
Administer as in adults
May potentiate doxorubicin-induced cardiotoxicity; may reduce digoxin serum levels and antimicrobial effects of quinolones; chloramphenicol may increase half-life while decreasing metabolite concentrations; coadministration with high doses of phenobarbital may increase rate of metabolism and leukopenic activity; inhibits cholinesterase activity for up to 10 d after an intravenous dose, which can potentiate the effect of succinylcholine chloride
Documented hypersensitivity; active infection; severely depressed bone marrow function
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Regularly examine hematologic profile (particularly neutrophils and platelets) to monitor for hematopoietic suppression; regularly examine urine for RBCs, which may precede hemorrhagic cystitis, especially when taking PO; obtain serial CBC counts and LFTs during course of treatment; monitor for leukopenia and elevated liver enzymes; increased risk of bladder cancer and hematologic malignancy; can cause sterility
Cyclosporine (Sandimmune, Neoral)
Cyclic polypeptide that suppresses cell-mediated immune reactions such as delayed hypersensitivity and, to a lesser extent, humoral immunity, allograft rejection, experimental allergic encephalomyelitis, and graft vs host disease for a variety of organs. Selectively inhibits transcription of IL-2, predominately in helper lymphocytes.
Adult
3-5 mg/kg/d PO divided bid
Pediatric
Administer as in adults
Carbamazepine, phenytoin, isoniazid, rifampin, and phenobarbital may decrease cyclosporine levels; macrolide antibiotics, triazole antifungal agents, calcium channel blockers, grapefruit juice, aminoglycosides, acyclovir, amphotericin B; may increase cyclosporine toxicity; acute renal failure, rhabdomyolysis, myositis, and myalgias increase when taken concurrently with lovastatin
Documented hypersensitivity; uncontrolled hypertension or malignancies; do not administer concomitantly with PUVA or UV-B radiation in psoriasis because of possibly increased risk of cancer
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Evaluate renal and liver functions often by measuring BUN, serum creatinine, serum bilirubin, and liver enzymes; may increase risk of infection and lymphoma; use IV only for patients who cannot take PO; raises serum uric acid level and increases risk of gout
Tumor necrosis factor inhibitors
These agents may be used in refractory cases of polymyositis that have failed to respond to conventional therapy with steroids.
Etanercept (Enbrel)
Binds specifically to TNF and blocks its interaction with cell surface TNF receptors, rendering TNF biologically inactive.
Adult
25 mg SC twice a week
Pediatric
0.4 mg/kg SC twice a week; not to exceed 25 mg/dose
None reported
Documented hypersensitivity; sepsis
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Caution in impaired renal function and asthma; discontinue administration if a serious infection develops; adverse effects may include injection site pain, localized erythema, rash, URTI symptomatology, GI upset, nausea, vomiting, rhinitis, and cough; congestive heart failure may worsen based on recent evidence; affects host defenses against malignancy and infections, although impact on infection and malignancy is not fully understood; may lead to formation of autoantibodies; local injection site reactions have been noted in about 37% of patients
Infliximab (Remicade)
Binds to soluble and transmembranous forms of TNF-alpha, rendering TNF biologically inactive.
Adult
3 mg/kg IV as an induction regimen at 0, 2, and 6 wk; repeat q2mo thereafter
Pediatric
Administer as in adults
None reported
Documented hypersensitivity; sepsis, NHYA class III/IV heart failure
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Anti-TNF therapies, such as infliximab, may adversely affect normal immune responses and allow development of superinfections (TNF-alpha modulates cellular immune responses); may increase risk of reactivation of tuberculosis in patients with particular granulomatous infections; caution in patients with recent neurological events such as demyelination of central nervous system or seizures, infections, and lymphoproliferative disorders; autoantibody production with lupuslike syndromes and injection-related infusion reactions reported
More on Polymyositis |
| Overview: Polymyositis |
| Differential Diagnoses & Workup: Polymyositis |
 Treatment & Medication: Polymyositis |
| Follow-up: Polymyositis |
| Multimedia: Polymyositis |
| References |
| « Previous Page | Next Page » |
References
Bohan A. History and classification of polymyositis and dermatomyositis. Clin Dermatol. Apr-Jun 1988;6(2):3-8. [Medline].
Schnabel A, Hellmich B, Gross WL. Interstitial lung disease in polymyositis and dermatomyositis. Curr Rheumatol Rep. Apr 2005;7(2):99-105. [Medline].
Cherin P, Pelletier S, Teixeira A, et al. Results and long-term followup of intravenous immunoglobulin infusions in chronic, refractory polymyositis: an open study with thirty-five adult patients. Arthritis Rheum. Feb 2002;46(2):467-74. [Medline].
Kumar A, Teuber SS, Gershwin ME. Intravenous immunoglobulin: striving for appropriate use. Int Arch Allergy Immunol. 2006;140(3):185-98. [Medline].
Hengstman G, Van den Housen F, Van Engelen B. Anti-TNF-blockade with infliximab (Remicade) in polymyositis and dermatomyositis. Arthritis and Rheumatology. 2000;43(9):S193.
Levine TD. Rituximab in the treatment of dermatomyositis: an open-label pilot study. Arthritis Rheum. Feb 2005;52(2):601-7. [Medline].
Alexanderson H. Exercise: an important component of treatment in the idiopathic inflammatory myopathies. Curr Rheumatol Rep. Apr 2005;7(2):115-24. [Medline].
Adams EM, Plotz PH. The treatment of myositis. How to approach resistant disease. Rheum Dis Clin North Am. Feb 1995;21(1):179-202. [Medline].
Aleksza M, Szegedi A, Antal-Szalmás P, Irinyi B, Gergely L, Ponyi A, et al. Altered cytokine expression of peripheral blood lymphocytes in polymyositis and dermatomyositis. Ann Rheum Dis. Oct 2005;64(10):1485-9. [Medline].
Amato AA, Barohn RJ. Idiopathic inflammatory myopathies. Neurol Clin. Aug 1997;15(3):615-48. [Medline].
Bohan A, Peter JB. Polymyositis and dermatomyositis (first of two parts). N Engl J Med. Feb 13 1975;292(7):344-7. [Medline].
Bohan A, Peter JB. Polymyositis and dermatomyositis (second of two parts). N Engl J Med. Feb 20 1975;292(8):403-7. [Medline].
Briani C, Doria A, Sarzi-Puttini P, et al. Update on idiopathic inflammatory myopathies. Autoimmunity. May 2006;39(3):161-70. [Medline].
[Best Evidence] Choy EH, Hoogendijk JE, Lecky B, et al. Immunosuppressant and immunomodulatory treatment for dermatomyositis and polymyositis. Cochrane Database Syst Rev. Jul 20 2005;CD003643. [Medline].
Dalakas MC. Polymyositis, dermatomyositis and inclusion-body myositis. N Engl J Med. Nov 21 1991;325(21):1487-98. [Medline].
Hicks JE. Rehabilitating patients with idiopathic inflammatory myopathy. Musculoskel Med. 1995;12:4-54.
Hill CL, Zhang Y, Sigurgeirsson B, et al. Frequency of specific cancer types in dermatomyositis and polymyositis: a population-based study. Lancet. Jan 13 2001;357(9250):96-100. [Medline].
Marie I, Hachulla E, Cherin P, et al. Opportunistic infections in polymyositis and dermatomyositis. Arthritis Rheum. Apr 15 2005;53(2):155-65. [Medline].
O'Rourke KS. Myopathies in the elderly. Rheum Dis Clin North Am. Aug 2000;26(3):647-72, viii. [Medline].
Oddis CV. Idiopathic inflammatory myopathies: a treatment update. Curr Rheumatol Rep. Dec 2003;5(6):431-6. [Medline].
Plotz PH, Miller F, Hoffman E, et al. Workshop on inflammatory myopathy Bethesda, 5-6 April 2000. Neuromuscul Disord. Jan 2001;11(1):93-5. [Medline].
Plotz PH, Rider LG, Targoff IN, et al. NIH conference. Myositis: immunologic contributions to understanding cause, pathogenesis, and therapy. Ann Intern Med. May 1 1995;122(9):715-24. [Medline].
Reimers CD, Finkenstaedt M. Muscle imaging in inflammatory myopathies. Curr Opin Rheumatol. Nov 1997;9(6):475-85. [Medline].
Salomonsson S, Lundberg IE. Cytokines in idiopathic inflammatory myopathies. Autoimmunity. May 2006;39(3):177-90. [Medline].
Spiera R, Kagen L. Extramuscular manifestations in idiopathic inflammatory myopathies. Curr Opin Rheumatol. Nov 1998;10(6):556-61. [Medline].
Targoff IN. Update on myositis-specific and myositis-associated autoantibodies. Curr Opin Rheumatol. Nov 2000;12(6):475-81. [Medline].
Henes JC, Heinzelmann F, Wacker A, Seelig HP, Klein R, Bornemann A, et al. Antisignal recognition particle-positive polymyositis successfully treated with myeloablative autologous stem cell transplantation. Ann Rheum Dis. Mar 2009;68(3):447-8. [Medline].
Further Reading
Keywords
polymyositis, PM, primary idiopathic polymyositis, idiopathic inflammatory myopathy, dermatomyositis, DM, inclusion body myositis, IBM, virus-mediated muscle injury, microvascular insult, collagen vascular disease
