NEW YORK - Pharmaceuticals-maker Bristol-Myers Squibb Co. said yesterday that it would lay off about 4,300 employees and close more than half of its manufacturing plants as part of a broad restructuring aimed at saving $1.5 billion by 2010.

The New York company, whose best-selling product is the blood thinner Plavix, also said it would spin off its medical-imaging business. In addition, Bristol-Myers is reviewing options for ConvaTec, a supplier of wound-care products, and its Mead Johnson Nutritionals business.

"It is difficult to see our valued colleagues leave the company, but right-sizing our workforce across all areas is critical to achieving our productivity goals and enhancing the competitive position of the company," chief executive officer James Cornelius said in a statement.

The job cuts, which represent 10 percent of the staff, will largely be made in 2008 and 2009, the company said.

It also said it would close more than half of its manufacturing facilities by the end of 2010.

Bristol-Myers has eight facilities across central New Jersey, including one in New Brunswick and several in and around Princeton. It was unclear how many of the job cuts would occur in New Jersey.

Cornelius is readying Bristol-Myers for the loss of more than $3 billion in annual revenue in 2012, when its top-selling Plavix faces generic competition. Bristol-Myers is preparing to shift its reliance to less-profitable drugs such as Erbitux for cancer, Sustiva for HIV, and Abilify for mental disorders.

Bristol-Myers raised its 2008 earnings forecast, excluding restructuring costs, to $1.65 to $1.75 a share from a previous projection of $1.60 to $1.70. The company's 2007 forecast of $1.42 to $1.47 a share was not changed.

Its shares rose 20 cents to close at $29.26 in New York Stock Exchange trading.