GlaxoSmithKline, one of the largest private employers in the Triangle, has begun layoffs as part of plans the company disclosed in October.

GSK (NYSE: ) operates one of its two U.S. headquarters in RTP, where some 5,000 people work.

The international pharmaceutical giant also operates a manufacturing facility in Zebulon that employs approximately 1,000 people.

GSK did not disclose the precise number of people being laid off .

“You will be hearing about this over time as we talk with people who are being affected,” GSK spokesperson Nancy Pekarek told “We are not giving out numbers and we are not confirming what groups or positions are being reorganized.”

In an earlier interview Pekarek noted that the restructuring is a “global program” and will take place over three years.

One Web site that follows GSK recently reported that some 100 people are likely to be laid off in Zebulon where the asthma drug Advair is manufactured.

The FDA said Thursday that it is may require GSK to change its labeling for Advair and another asthma drug Serevent due to potential health risks to children.

GSK disagreed with the recommendation, which was made to the FDA by a panel of advisers.

"There is no new safety information that changes the benefit-risk evaluation of Serevent or Advair which warrants another review at this time," Glaxo said in a statement.

Advair produced $6.8 billion in sales a year ago.

Revenues at GSK have been under heavy pressure since May when a report in the New England Journal of Medicine questioned the safety of the company’s $2.8 billion dollar selling diabetes drug Avandia. Sales of Avandia plummeted following the report, and the U.S. Food and Drug Administration required GSK to change its labeling on the product.

GSK said last month that it would close a manufacturing facility for Avandia in Puerto Rico. The plant employs some 900 people.

GSK shares closed at $52.22 Thursday, up 74 cents.