Several medications may be used to manage the symptoms of dermatomyositis (DM) and polymyositis (PM). These drugs may also be used to treat inclusion body myositis (IBM). However, most reports suggest that these drugs provide minimal, if any, improvement in symptoms with IBM.

Prednisone (Deltasone; Orasone) is the corticosteroid of choice for treating myositis. This is a synthetic hormone that suppresses abnormal actions of the immune system, thereby causing fewer inflammatory cells to be produced. The most common short term side effects of prednisone are increased appetite leading to weight gain, easy bruising, mood swings, irritability, and leg cramps. Long term side effects are loss of calcium from the bone and an increased risk of developing diabetes, especially if other close family members have the disease. Other side effects may occur if the drug is stopped too quickly. To reduce the risk of these disorders, prednisone is usually given in high doses for only a short time. Prednisone is then tapered by giving a high dose one day and a low dose the next day. Over time, the amount of the high dose is reduced.

It usually takes about three to four months to reach the full effect of prednisone. About 75% of patients with PM or DM respond with prednisone treatment alone. Other patients may need a combination of prednisone and another drug.

While you're taking prednisone, call your doctor immediately if you experience a skin rash; black or tarry stools; swollen face, ankles, or legs; vision problems, or a cold that won't go away. In addition, consult your doctor if you experience any of the following side effects: upset stomach, vomiting, headache, dizziness, depression, anxiety, restlessness, insomnia, acne, unusual hair growth, easy bruising, and a change in menstrual periods.

Immunosuppresant agents include azathioprine (Imuran), methotrexate (Folex;, Rheumatrex), cyclophosphamide (Cytoxan;, Neosar), and cyclosporine (Sandimmune;, Neoral). These drugs suppress the immune system, which causes a decreased production of inflammatory cells. In some cases, these drugs may be used alone. Often, these drugs are used along with prednisone.

Immunosuppressant drugs suppress your immune system, so your doctor should know about any illness or lingering infection you develop. Call your doctor immediately if you develop a cough or hoarseness, fever or chills, difficult or painful urination, or a pain in the lower back or side. Also, check with him or her if you notice small red spots on your body, dark or tarry stools, or blood in the urine. You should avoid immunizations while you're taking these drugs, and stay away from anyone who has had an oral polio vaccine (there's a possibility you could contract the virus).

Among the common immunosuppressant drugs:

Azathioprine

It usually takes four to eight months for the effect of azathioprine to be felt. Symptoms may return within two to three months after the drug is stopped.

Most patients tolerate azathioprine well. However, in 15 percent of patients, azathioprine causes an acute flu-like illness (achy joints and muscles) that goes away promptly after stopping the drug. Azathioprine can produce a decrease in the number of white blood cells, red blood cells, and platelets. Patients need a CBC (complete blood count) test at regular intervals while using this drug. A CBC measures the number of blood cells in the body. Methotrexate

Methotrexate is taken once each week. Taking the same dosage on a daily basis could lead to a fatal drug overdose.

In some patients, methotrexate causes a decrease in the number of white blood cells, red blood cells, and platelets. It can also cause problems in the liver, problems in the kidney and shortness of breath. While taking this medication, it is important to have frequent blood cell count tests, tests of liver function and tests of kidney function.

Cyclophosphamide

Cyclophosphamide is usually used only for the most severe cases of PM and DM. Patients who take cyclophosphamide must have frequent CBC testing.

Cyclosporine

Cyclosporine may be used with patients who have not responded to other treatments. It is expensive and can have significant side effects. The most common ones include hypertension, headache, painful or swollen gums, nausea, vomiting, increased hair growth, and tremors. Use of cyclosporine can also cause kidney problems, so tests are performed at regular intervals to monitor kidney function while patients are using this drug.

First published April 1, 2000
Last updated August 1, 2003
Copyright © 2000 Accordant Health Services, Inc. All Rights Reserved.

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