Biogen Idec announced that Avonex (Interferon beta-1a), the most prescribed multiple sclerosis (MS) therapy worldwide, is now available in Japan. Avonex is available in more than 90 countries, and its introduction in Japan extends Biogen Idec's leadership in the treatment of MS to an important and underserved market.

In July 2006, the Japanese Ministry of Health, Labour and Welfare approved Avonex for the prevention of MS relapse. Avonex is the first new MS treatment available in Japan in six years. It is the second disease-modifying therapy approved to treat MS in Japan and the only one that can be administered once a week. In international clinical trials, Avonex has been proven to slow the progression of disability and reduce the frequency of clinical relapses, as well as delay the development of clinically definite MS.

"For more than a decade, Biogen Idec has been committed to advancing the treatment of MS, and we look forward to extending that dedication to serve patients and their families in Japan," said James C Mullen, president and chief executive officer, Biogen Idec. "The introduction of Avonex to the Japanese MS community continues our mission of delivering important therapeutics to patients around the world."

There are approximately 12,000 people diagnosed with MS in Japan. However, a number of patients are believed to be undiagnosed. In addition, many Japanese patients are treated with acute rather than long-term therapy, and there are a number of patients who have discontinued therapy due to perceived lack of efficacy or side effects. Initially, Avonex will be introduced in Japan to hospitals with MS experts, and then Biogen Idec expects it will become more widely available.

"Avonex is the leading choice for prescribing physicians and their MS patients because it offers proven efficacy and a convenient dosing regimen that patients can adhere to over the long term," said Toshio Nakata, president of Biogen Idec Japan. "MS is a debilitating disease that remains under-treated in Japan, and we believe patients can benefit greatly from the availability of a new treatment option."

Avonex is the most prescribed treatment for relapsing forms of MS worldwide, with more than 130,000 patients on therapy. It was launched in the US in 1996 and later in Europe for the treatment of relapsing forms of MS to slow the progression of disability and reduce relapses. Avonex is marketed internationally in more than 90 countries. Avonex was the first treatment approved for patients who have their first clinical MS attack and have a brain MRI scan consistent with MS; this use was approved in Europe in 2002 and in the US in 2003.

The most common side effects associated with Avonex multiple sclerosis treatment are flu-like symptoms, including myalgia, fever, fatigue, headache, chills, nausea, vomiting, pain and asthenia.

Avonex should be used with caution in patients with depression or other mood disorders and in patients with seizure disorders. Avonex should not be used by pregnant women. Patients with cardiac disease should be closely monitored. Patients should also be monitored for signs of hepatic injury. Routine periodic blood chemistry and haematology tests are recommended during treatment with Avonex. Rare cases of anaphylaxis have been reported.