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Multiple Sclerosis (MS) Medications (cont.)

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What are disease modifying drugs, and which ones are available?

Disease modifying drugs (DMDs) slow the progression (degeneration) of MS and by reducing the frequency and severity of acute attacks and preventing permanent damage to nerves. They are most effective when started early in the course of the disease.

Interferon beta-1a, the active chemical in Avonex and Rebif, is a naturally occurring protein found in the body. Avonex and Rebif are synthesized using recombinant DNA technology, and the synthetic chemicals are identical to the natural protein. The mechanism of action of interferon beta-1a in MS is unknown. Avonex and Rebif are used for the treatment of patients with relapsing forms of MS to slow the progression of physical disability and decrease the frequency of flare ups.


Avonex is administered by intramuscular injection once a week. In clinical studies disease progression was slower in Avonex treated patients. Compared to patients treated with placebo, the risk of progressive physical disability was reduced by 37% in patients treated with Avonex. Side effects associated with Avonex include flu-like symptoms, depression, abnormal liver tests, a drop in red and white blood cells and platelets. Allergic reactions, seizures and heart failure also have been associated with Avonex. Avonex should not be used during pregnancy due to the risk of miscarriage or harm to the fetus.

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