CAMBRIDGE, Mass. ( TheStreet) -- Biogen Idec ( BIIB - Get Report) reported a 14% increasse in adjusted third-quarter earnings as sales of its multiple sclerosis drug Tysabri slightly exceeded Wall Street expectations.

The company slightly lowered revenue guidance for the rest of the year.

Third-quarter net income totaled $278 million, or 95 cents a share, compared with net income of $207 million, or 70 cents a share, in the year-earlier period.

On an adjusted basis, Biogen earned $1.12 cents a share, higher than the $1.04 a share consensus estimate of analysts surveyed by Thomson Reuters.

Third-quarter revenue rose 3% to $1.12 billion from $1.09 billion a year ago, slightly ahead of the consensus forecast of $1.11 billion.

Worldwide sales of the multiple sclerosis drug Tysabri totaled $279 million in the third quarter, ahead of the consensus estimate of $273 million.

The company said 46,200 patients were being treated with Tysabri at the end of September, up from 43,000 patients treated at the end of the June quarter. But that translates into a decline in the number of new patient starting on Tysabri, with 223 new patients adds per week in the third quarter, down from 262 new patient adds per week in

Biogen shares Tysabri revenue with Irish drug maker Elan ( ELN). Biogen recognized $207 million in revenue from Tysabri in the quarter.

Third-quarter sales of the multiple sclerosis drug Avonex rose 1% to $580 million.

Looking ahead, Biogen revised its 2009 revenue guidance to "mid to high single digit" percentage growth from its previous estimate of "high single digit" growth. The company said it expects adjusted earnings to be "above $3.85 a share" compared to current consensus of $3.92 a share on $4.38 billion.

Biogen also announced a $1 billion share repurchase program.Biogen shares closed Wednesday at $49.39.

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