The battle for the top job at the world’s second-largest drug company will reach a climax this month when the board of GlaxoSmithKline meets to decide on a successor to JP Garnier, the chief executive.

Dr Garnier, who will be 60 this month, is due to step down in May. The board, led by Sir Christopher Gent, the chairman, is to meet in the run-up to the group’s third-quarter results on October 24 to decide on his replacement.

It has developed into a three-way struggle between internal candidates: Chris Viehbacher, president of Glaxo’s American pharmaceuticals business; Andrew Witty, president of European pharmaceuticals; and David Stout, the president of pharmaceuticals operations.

The three men have been openly competing for the job for two years.

Another early contender, Russell Grieg, head of international operations, is thought to be no longer in the running. Insiders say that if the board is split and a final decision cannot be reached by the end of this month, it could be delayed until early December when the board has its final meeting of the year.

An announcement on the succession is expected early next year. The successful candidate will inherit control of a pharmaceutical company with more than £20 billion in annual sales and one of the strongest pipelines of new drugs in the industry.

However, he will also face growing pressure from investors to end the furore surrounding Avandia, the diabetes medicine, which is Glaxo’s second-biggest-selling product. It has been linked to a significantly increased risk of heart disease.

The new man may also face calls to consider a sale of Glaxo’s consumer healthcare unit, the owner of Ribena and Lucozade, which some critics have claimed is not a core part of the business.

Mr Viehbacher, 48, who is based at the group’s American head office in Philadelphia, is considered to be more hands-on and more aggressive in terms of strategy than his rivals.

“He is more of a JP type,” said one source, who also pointed out that he had enjoyed greater access to the chief executive than his rivals.

Mr Viehbacher, a dual Canadian-German citizen, joined Wellcome in 1988 and became director, continental Europe, at Glaxo Wellcome in 1999. He was responsible for GSK’s European pharmaceuticals business before taking up his present appointment in January 2003.

Andrew Witty, who is 44 and British, is considered to be more reserved and willing to allow others to take responsibility.

Mr Stout, an American who, at 54, is the oldest of the contenders – a factor that some observers believe may work against him – is responsible for the global pharmaceuticals and vaccines businesses.

His greatest strength is his experience and influence in Washington.

Mr Stout joined SmithKline Beecham in 1996 as head of its American sales and marketing, and operated as president of US pharmaceuticals until taking up his present appointment in January 2003.

The candidates have each been asked to oversee a special project for the company to assist the board in its selection process. Mr Viehbacher has been set the task of improving “pharmaco-vigilance” at GSK and the way in which the company monitors safety issues.

Mr Witty has been leading a drive on marketing and exploring ways that GSK could improve the group’s sales operation. Mr Stout has been examining the potential for greater outsourcing in Glaxo’s manufacturing operation.

A GSK spokesman said: “The process is ongoing. We have some strong internal candidates and when the board has made a decision we will announce it in the usual way.”

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