Beta-interferon is licensed in Singapore for use in patients with relapsing-remitting multiple sclerosis to reduce the frequency of clinical exacerbations. Both Betaferon® (Zuellig Pharma) and Rebif® (Serono) have been registered in Singapore since 1999. Beta-interferon belongs to the family of naturally occurring proteins interferons that are expressed in response to viral infections and other biologic agents. Beta-interferon has been shown to possess both antiviral and immunoregulatory activities but the mechanism of action in patients with MS is unknown.

Recently, the regulatory authority in Canada issued a public advisory and a Dear Healthcare Professional Letter to warn of the rare occurrence of post-marketing cases of serious hepatic injury, including autoimmune hepatitis, hepatitis and hepatic failure, in MS patients treated with beta-interferon. (Rare reporting occurrence is defined as a reporting rate of between 1/1,000 and 1/10,000). In addition to the post-marketing reports, serious liver toxicity has also been reported in the literature for all beta-interferon products.

To date, there are 3 cases worldwide of hepatic failure requiring liver transplantation. No local report of liver toxicity associated with the use of beta-interferon has been reported to HSA.

Post-marketing experience has shown that serious hepatic injury occurs predominantly in the first 6 months of therapy. Cases of liver toxicity have been reported in patients on therapy beyond 1 year. Patients' baseline liver function should be measured prior to initiating of beta-interferon therapy. Prescribers are reminded to monitor patients' liver function very closely for the first 6 months of therapy and every 6 months thereafter.