As part of its 2Q11 earnings announcement, Merck revealed that it plans to expand its current restructuring plan. The company will lay off 11 to 12% of its staff (around 10,500 of its 91,000 employees) in an effort to gain approximately $1.5 billion in annual savings by 2015. The layoffs come on top of the initial post-Schering-Plough restructuring announcement in November 2009, which involved 16,000 layoffs for a planned savings of $2.7 to $3.1 billion. The total cost of all restructuring is estimated between $5.8 and $6.6 billion.

“Merck is taking these difficult actions so that we can grow profitably and continue to deliver on our mission well into the future,” said Merck’s president and chief executive officer, Kenneth C. Frazier. “The environment we operate in is changing rapidly and dramatically, and these steps will help us more efficiently serve customers and patients around the world.

The company will begin to lose patent protection for its top seller, Singulair, in mid-2012. That drug posted revenues of $5.0 billion in 2010 and $2.7 billion in the first two quarters of 2011.

UPDATE: According to a Merck SEC filing, “[a] majority of the workforce reductions in this new phase of the Merger Restructuring Program will occur in manufacturing, including Animal Health, administrative and headquarters organizations.” Also, “The Company will continue to pursue productivity efficiencies and evaluate its manufacturing supply chain capabilities on an ongoing basis which may result in future restructuring actions.” Most of the activity from this phase will be done by 2013, “with the exception of certain manufacturing actions which are expected to be completed by 2015.”

Read our profile of Merck in this year’s Top 20 Pharma Report!