Drug maker Biogen Idec Inc. on Thursday said it will lay off 650 workers, or about 17 percent of its work force, as part of a plan to reduce annual expenses by $200 million to $300 million.

The Cambridge-based biotechnology firm, seeking to regain its footing after withdrawing a multiple sclerosis drug over safety concerns, said it also plans to sell a San Diego manufacturing plant as well as the rights to Amevive, a psoriasis drug that generated $43 million in sales last year.

James C. Mullen, Biogen Idec's chief executive and president, said the company is "well-poised for near-term success'' but believes for the long term that it must cut programs "unlikely to create significant value.''

Biogen Idec announced the restructuring after its shares closed down 3 cents at $42.44 on the Nasdaq Stock Market, where the stock has traded in a 52-week range of $33.18 to $70.

Biogen Idec said the cuts to 650 positions worldwide will mostly occur by the end of the year, spread across various departments and locations. Of the total jobs to be cut, 250 will come from the company's Cambridge headquarters, which now has 1,700 employees.

Biogen Idec expects to take a pretax charge against its earnings of $30 million to $40 million to cover severance and restructuring costs resulting from the cuts.

The company has recently remained profitable despite its decision in February to withdraw the multiple sclerosis drug Tysabri. Biogen Idec developed the drug with its Irish partners, Elan Inc.,

The drug may heighten the risk of contracting a rare and often fatal disease of the central nervous system. The companies are completing a review of the drug's safety, and hope to report back to federal regulators by month's end in hopes that it will be found safe to return to the market, likely with a more restrictive warning label.

The drug was withdrawn after it was linked to two cases of a brain disease called progressive multifocal leukoencephalopathy, or PML. One of those patients died. On March 30, Elan and Biogen announced that a Crohn's sufferer who had been taking Tysabri also had died of PML

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