Merck & Co president Kenneth Frazier will succeed Richard Clark as the drugmaker's chief executive officer, effective Jan 1, the company said on Tuesday.

Frazier's promotion has been expected after he was named to the role of president earlier this year. Clark, who in March turns 65, the mandatory company CEO retirement age, will continue as chairman.

Frazier, who joined Merck in 1992, was previously president of the company's global pharmaceuticals division. He also served as the company's general counsel when Merck's Vioxx painkiller was withdrawn from the market because of an increased risk of heart attack and stroke. Frazier helped the company fight off thousands of personal injury lawsuits related to the drug's use. Merck eventually settled the litigation for about $4.85 billion, billions less than investors had feared, boosting Frazier's profile within Merck and with Wall Street.