Profile: Biogen Idec focuses on the discovery and development of therapies. Avonex® is the most prescribed treatment for relapsing forms of multiple sclerosis to slow down the progression of disability and to reduce relapses. This is also recommended for patients who have their first clinical multiple sclerosis attack and have a brain MRI scan consistent with multiple sclerosis. This should be used with caution in patients with depression or other mood disorders and in patients with seizure disorders. This is not applicable for pregnant woman. Patients with cardiac disease should be closely monitored. Patients should also be monitored for signs of hepatic injury. Rare cases of anaphylaxis have been reported. Tysabri® is a treatment approved for relapsing forms of MS. This has been recently approved to induce and maintain clinical response and remission in adult patients with Crohn's disease. This increases the risk of progressive multifocal leukoencephalopathy (PML), a viral infection of the brain that usually leads to death or severe disability. Rituxan® is approved for use in combination with methotrexate for reducing signs and to slow down the progression of structural damage in adult patients suffering from rheumatoid arthritis.