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How It Works

Glatiramer acetate (formerly known as copolymer-1) is an artificial protein that resembles a natural myelin protein. It is not known exactly how the medication works, but it may help people who have multiple sclerosis (MS) by preventing the body's immune system from attacking the myelin coating that protects nerve fibers.

Glatiramer acetate is given as an injection beneath the skin one time a day. An oral tablet form has been tested but failed to show any benefit for people with MS.

Why It Is Used

Glatiramer acetate may be used to treat people 18 years or older who have relapsing-remitting MS. It is not approved to treat other forms of MS.

How Well It Works

Glatiramer acetate significantly reduces the frequency of relapses in those with relapsing-remitting MS. It also slows the number of new lesions (tissue damage) as seen on MRI and decreases disability.¹

Glatiramer acetate can slow the rate of new lesions in those with relapsing-remitting MS, without the flu-like symptoms that interferon beta medications can cause.¹ However, it may not be as effective at reducing disability as interferon beta.²

Glatiramer acetate has not been shown to be effective for people who have secondary progressive MS. Also, the medication is not helpful for people who have primary progressive MS.

Side Effects

Some people may have temporary side effects right after the shot (post-injection reaction), which can include:

• Pain, redness, or swelling at the injection site.
• Flushing.
• Chest pain, rapid heartbeat, and shortness of breath similar to that experienced in a heart attack.
• Anxiety.
• Tightness in the throat.

These side effects are usually mild and go away on their own shortly after the injection. You may have one or several brief episodes of these side effects during your treatment with glatiramer acetate.

Although less common, other side effects may occur, including:

• Weakness.
• Nausea.
• Joint pain.
• Severe muscle tension or spasticity.
• Skin rash.
• Impotence or decreased interest in sex.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Glatiramer acetate may be used if you have tried interferon beta and the medication has not been effective or you cannot tolerate the side effects. Generally, glatiramer acetate is well-tolerated and does not cause the flu-like side effects that occur when taking interferon beta medications. However, it may take up to 7 months for any benefit from glatiramer acetate to occur. Benefit from interferon beta occurs within 1 month of starting treatment. Sometimes, glatiramer acetate is the first medicine tried.

Treatment with glatiramer acetate should not be started until it is clear that you have the relapsing-remitting form of MS. The National Multiple Sclerosis Society recommends that treatment with glatiramer acetate or one of the interferon medications be started as soon as a clear diagnosis is made.³

The safety of glatiramer acetate during pregnancy and breast-feeding is not known. Talk to your doctor if you are planning a pregnancy, if you are pregnant, or if you are breast-feeding.

In addition to side effects, there are some drawbacks to treatment with glatiramer acetate:

• Treatment is not effective at all for some people, and it is hard to predict whether the medication will help a particular person.
• The long-term risks of treatment are unknown. It is possible that long-term use of the medication may lower the body's defense against other diseases. For people with mild MS, the benefits may not be worth the possible risks.
• Treatment may cost more than $15,000 per year.

If you are taking glatiramer acetate, do not stop taking it without first talking with your doctor.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.

Citations

1. Simpson D, et al. (2003). Spotlight on glatiramer acetate in relapsing-remitting multiple sclerosis. Biodrugs, 17(3): 207–210.

2. Sadiq SA (2005). Multiple sclerosis. In LP Rowland, ed., Merritt's Neurology, 11th ed., pp. 941–963. Philadelphia: Lippincott Williams and Wilkins.

3. National Clinical Advisory Board of the National Multiple Sclerosis Society (2007). Disease Management Consensus Statement. New York: National Multiple Sclerosis Society. Available online: http://www.nationalmssociety.org/site/PageServer?pagename=HOM_PRO_expert_opinion_papers.

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