Merck (NYSE:MRK) on Tuesday named Kenneth Frazier as the drug maker’s new chief executive, effective Jan. 1.

Frazier, currently Merck’s president, is replacing Richard Clark, who has served in the top spot since 2005 and will continue as chairman of the board.

“Merck’s board of directors and I have great confidence in Ken as the right CEO to lead this exceptional company into a new era of global health care,” Clark said in a statement, noting Frazier has made “considerable contributions” in his 18 years with the company.

Since his appoint to president in April, Frazier focused on improving the effectiveness of the company’s largest divisions; pharmaceutical and vaccine sales and marketing, research and development, and manufacturing and supply. He also helped with post-merger integration and assisted in creating the company’s new global commercial sales model.

"His intellect, drive and deep understanding of our industry will greatly benefit Merck and our mission of improving and saving lives through scientific innovation," Clark said.

Prior to serving as president, Frazier headed Merck’s global human health unit, and even earlier served as vice president, general counsel and secretary of the Astra Merck Group.

Frazier, who will also join the company’s board of directors, currently sits on the board of Exxon Mobil (NYSE:XOM), Pennsylvania State University and Cornerstone Christian Academy in Philadelphia.

As chairman, Clark, whose career at Merck spans 38 years, will focus on the board’s leadership, while providing strategic counsel to Frazier and overseeing the planned formation of Merck’s joint venture in animal health with Sanofi-Aventis (NYSE:SNY).