Interferons for relapsing multiple sclerosis

Since 1993, medications that alter the immune system, particularly interferons, have been used to manage multiple sclerosis. Interferons are protein messengers that cells of the immune system manufacture and use to communicate with one another. There are different types of interferons, such as alpha, beta, and gamma. All interferons have the ability to regulate the immune system and play an important role in protecting against intruders including viruses. Each interferon functions differently, but the functions overlap. The beta interferons have been found useful in managing multiple sclerosis.

• Interferon beta-1b (Betaseron®) was the first interferon approved in the U. S. to manage RR-MS in 1993.
• In 1996, intramuscular interferon beta-1a (Avonex®) gained FDA approval for RR-MS.
• Subcutaneous Interferon beta-1a (Rebif®) was approved in the U. S. in 2002.
• The FDA also approved the marketing of Interferon beta-1b under the brand name Extavia® in 2009.

Overall, patients treated with interferons experience fewer relapses or a longer interval between relapses. Avonex® and Rebif® are used to slow progressing disability. The most common side effect is a flu-like syndrome that includes fever, tiredness, weakness, chills, and muscle aches. This syndrome tends to occur less frequently as therapy continues. Other common side effects are injection site reactions, changes in blood cell counts, and abnormalities of liver tests. Regular liver tests and blood counts are recommended for patients receiving beta-interferons. Periodic thyroid function testing also is recommended because of the effects of beta-interferons on the thyroid gland. With the concomitant use of analgesics and evolving nursing experience with managing local skin reactions, the tolerability to interferons seems to have improved over the years.

Clinical trials of beta-interferon in patients with the first attack of multiple sclerosis showed that in this early patient population, the second attack was delayed. Interferons approved by the FDA for treatment at the first attack of multiple sclerosis include Avonex®, which is administered intramuscularly once a week, and Betaseron® or Extavia®, which are administered subcutaneously every other day.

Available beta-interferons include:

Interferon beta-1b (Betaseron® and Extavia®) are used for the treatment of relapsing forms of multiple sclerosis, to reduce the frequency of clinical relapses. 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.

Interferon beta-1a (Rebif®) is used for the treatment of patients with relapsing forms of multiple sclerosis to decrease the frequency of clinical relapses and delay the accumulation of physical disability. Efficacy of Rebif® in chronic progressive multiple sclerosis has not been established.

Interferon beta-1a (Avonex®) is used for the treatment of patients with relapsing forms of multiple sclerosis to slow the accumulation of physical disability and decrease the frequency of clinical relapses. 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 progressive multiple sclerosis has not been established.

References: http://www.medicinenet.com