By Steve Usdin
Contributing Editor

WASHINGTON -- The FDA announced on Friday the final approval of Chiron Corp.'s Betaseron interferon beta 1b, the first treatment for multiple sclerosis and the first biotechnology product to be licensed under the agency's accelerated approval regulations. 

However, Chiron is scrambling to ramp up production and expects supply to fall below demand for 18 months.

Betaseron was approved for use in ambulatory patients with relapsing- remitting MS to reduce the frequency of clinical exacerbations. About 30 percent of the 250,000 to 350,000 Americans who are affected by MS suffer from the relapsing-remitting form, according to the FDA.