Merck is acquiring Schering-Plough for $41.1 billion in a bid to bolster its pipeline, broaden its global presence and strengthen its specialty sales force.

The merger, the company said in a release, “will double the number of potential medicines Merck has in Phase III development” to 18, including Schering-Plough’s novel thrombin receptor antagonist. The deal also strengthens Merck’s commercial organization through Schering-Plough’s “focus on specialty therapeutic areas and its strength in international markets.” And the merger will help Merck bump the share of its revenue generated outside the US to more than 50%, the firm said.

The combined company, to be called Merck, will be led by Merck CEO Richard Clark, who will serve as chairman, president and CEO. Schering-Plough chief Fred Hassan “is committed to continuing the strong operations at Schering-Plough and intends to participate in the integration planning until the close.” Together, Merck and Schering-Plough had revenues of $47 billion in 2008.

Merck and Schering-Plough have long partnered on a joint venture cholesterol franchise that included Zetia and Vytorin. The integration of that joint venture was cited as a prime contributor to a projected $3.5 billion annual cost savings Merck expects to reap from the merger.

Merck called retaining top talent from both organizations a key priority and expects that “the substantial majority” of Schering-Plough staff will remain at the combined company. Both companies instituted immediate hiring freezes.