United States of America - Interferon beta-1a (Avonex®) was introduced to the United States market in 1996. In post-marketing experience severe hepatic injury, including hepatic failure, has been reported rarely. In some cases, these events have occurred in the presence of other drugs that have been associated with hepatic injury. The potential for hepatic injury should be considered when interferon beta-1a is used in combination with other products associated with hepatic injury, or when new agents are added to the regimen of patients already on

In March 2005, the prescribing information and medication guide were updated to include this important new safety information including precautions for patients and pregnancy.

Reference: Communication from Biogen dated 1 March 2005, posted on http://www.fda.gov/medwatch