Generally, these medications tend to decrease the frequency of attacks in patients with mild-to-moderate relapsing remitting MS (RRMS) by 18% to 33%. The rate of new lesions that appear on magnetic resonance imaging (MRI) is also reduced by approximately one-third. With the interferon drugs, the effectiveness is directly related to the dose (higher doses of IFN, if tolerated, are generally more effective). Whether the delay in the onset of new attacks by these drugs ultimately has a long-term impact on the disability associated with multiple sclerosis is controversial. However, clinical trials suggest that patients receiving early treatment have a beneficial impact on relapses and disability that may not be matched by patients in whom the treatment is delayed. Research regarding this continues.

The ability to respond to long-term interferon beta-1a and beta-1b may be limited, in some patients, by the development of persistent, high titer neutralizing antibodies. Patients treated with glatiramer also eventually develop antibodies, but these antibodies do not seem to limit glatiramer's activity.

How immune-altering drugs work:

• Interferons are thought to decrease the ability of immune cells to interact with other cells, to penetrate the blood brain barrier, and to produce the swelling and inflammation that is associated with demyelination.



• Glatiramer acetate (Copaxone) is a mix of amino acids that may mimic myelin proteins. It has a mechanism of action that seems to differ from that of interferons. The theory is that the amino acid mixture causes white blood cells that would attack myelin to bind instead to the drug. This interaction leads to a decrease in the immune cell reactivity towards the CNS, and some have proposed that the cells become regulatory (or helpful) agents that counteract damage.

Indications in the U.S. for Treatment with Immune-Modulating Drugs for Multiple Sclerosis

IFN beta-1b (Betaseron): indicated for the treatment of relapsing forms of multiple sclerosis, to reduce the frequency of clinical exacerbations. Patients with multiple sclerosis in whom efficacy has been demonstrated include patients who have experienced a first clinical episode and have MRI features consistent with multiple sclerosis.

IFN beta-1a (Rebif): indicated for the treatment of patients with relapsing forms of multiple sclerosis to decrease the frequency of clinical exacerbations and delay the accumulation of physical disability. Efficacy of Rebif in chronic progressive multiple sclerosis has not been established.

IFN beta-1a (Avonex): indicated for the treatment of patients with relapsing forms of multiple sclerosis to slow the accumulation of physical disability and decrease the frequency of clinical exacerbations. Patients with multiple sclerosis in whom efficacy has been demonstrated include patients who have experienced a first clinical episode and have MRI features consistent with multiple sclerosis. Safety and efficacy in patients with chronic progressive multiple sclerosis have not been established.

Glatiramer acetate (Copaxone): indicated for reduction in the frequency of relapses in patients with relapsing-remitting multiple sclerosis.

• Who should not use these medications:
  
  
  • Individuals allergic to any of these drugs
  
  
  
  • Women who are pregnant or breastfeeding
  
  
  
  • Individuals with impaired liver function
  
  
  
  • Individuals with a low platelet or white blood cell count
    
    

• Use: The immune-modulating drugs described above are administered by an injection under the skin [subcutaneous, as for glatiramer acetate (Copaxone), IFN beta-1a (Rebif) and IFN beta-1b (Betaseron) or into the muscle (intramuscular, as for IFN beta-1a [Avonex]). Depending on which drug is prescribed, the frequency of administration may be every day (Copaxone), every other day (Betaseron), 3 times per week (Rebif), or once a week Avonex.



• Drug or food interactions: No known drug interactions have been reported.



• Side effects: Interferons may cause a flu-like reaction that can be minimized by taking acetaminophen, aspirin, or ibuprofen several hours before the dose. Tenderness, redness, or swelling may occur at the injection site. Pregnant women should not use interferons. Interferons may also cause liver toxicity, decreased white blood cell and platelet counts, and worsening of thyroid disease, seizures, or depression.