Biogen Idec reported fourth-quarter results that topped expectations and issued a better-than-expected 2011 forecast today.

The US-based biotechnology company said net profit fell 21 per cent to $240 million, or 99 cents a share due to restructuring, but sales of its multiple sclerosis drug Tysabri rose 12 per cent to $333 million.

Revenue rose 8 per cent to $1.22 billion, driven mainly by sales of Tysabri, which Biogen sells in partnership with Irish pharmaceutical firm Elan.

Excluding one-time items, Biogen earned $1.42 a share. Analysts on average expected the company to earn $1.23 a share on revenue of $1.17 billion. The results were helped by a lower tax rate.

Sales of the company's multiple sclerosis drug Avonex rose 10 percent to $654 million.

The company said it expects 2011 earnings excluding one-time items to top $5.70 a share, and 2011 revenue growth to be between flat and the low single digits.

Analysts on average are expecting 2011 earnings excluding items of $5.63 per share and revenue of $4.68 billion.

Biogen said it estimates that about at the end of December about 56,600 patients were taking Tysabri worldwide, an increase of 1,700 patients in the fourth quarter and 8,200 in 2010.

Biogen is battling to maintain market share as new competitors enter the market. In September, Swiss drugmaker Novartis AG introduced Gilenya, the first multiple sclerosis pill. Drugs like Avonex and Tysabri must be injected or infused.

Novartis recently reported that in the first quarter of the drug's launch in the United States, 2,000 patients were on the drug at the end of 2010.

The company said about 50 per cent of Gilenya patients had been treated with a different MS drug within the prior 12 months and of these, 80-85 per cent switched from an injectable drug, including Avonex, and 10-15 per cent switched from Tysabri, which is infused.

"We continue to believe that switching from Tysabri to Gilenya will be modest," said Thomas Wei, an analyst at Jefferies & Company, in a recent research note

Biogen is working on its own oral MS drug, known as BG-12, and expects to report data from two late-stage trials later this year.

Tysabri was temporarily withdrawn from the market in 2005 after being linked to a potentially deadly brain disorder known as progressive multifocal leukoencephalopathy, or PML. Widely considered the most effective drug on the market, it was brought back with stricter safety warnings in 2006.

As of January 7th, the overall incidence of PML was 1.06 per 1,000 patients and the total number of cases associated with the drug is 85. Of those, 16 patients have died, while 69 are still alive with varying degrees of disability.

Biogen's shares rose 3 per cent to $67.50 in premarket trading.

Reuters