LONDON (Reuters) - The United States and China will be key focuses for the consumer healthcare venture being formed by GlaxoSmithKline and Pfizer, as the companies look to build on strong existing positions in those markets.

FILE PHOTO: Brian McNamara, CEO of GSK Consumer Healthcare, poses for a picture at the company's office in London, Britain April 4, 2019. REUTERS/Martinne Geller/File Photo

GSK and Pfizer are on track to create the world’s biggest consumer health business - with brands from Advil painkillers to Chapstick lip balm - by the second half of 2019, Brian McNamara, CEO of GSK Consumer Healthcare, told Reuters on Thursday.

The venture, to be 68 percent owned by GSK, will become a stand-alone company within three years of closing the deal, and McNamara will lead it.

“The U.S. and China are really two of the key value drivers of the deal because it’s where Pfizer has critical mass and a significant amount of their key brands,” he said in an interview, noting the new entity will be the No.1 player in the United States and No.2 in China. “U.S. and China are must-win markets.”

The consumer health sector, which spans vitamins, non-prescription medicines and other drug store purchases, is buoyed by ageing populations, a growing interest in health, wellness and self-care, and growing middle classes. It has slowed at times in recent years, due to emerging market fluctuations or weak flu seasons.

The new, yet-to-be-named company will have annual sales of 9.8 billion pounds ($12.9 billion) and more than 7 percent of the global consumer health market, with brands also including Centrum vitamins and Sensodyne toothpaste.

That puts it ahead of rivals Johnson & Johnson, Bayer and Sanofi.

Pfizer’s Centrum is already the leading multivitamin in China, while Caltrate is the No.2 calcium supplement in what is one of the world’s most calcium-deficient populations, McNamara said.

He said vitamins, minerals and supplements (VMS) would be a major focus, alongside oral care and over-the-counter pain medicine, and respiratory treatments like cold and flu tablets.

“It gives us the presence globally but it really strengthens our China position,” he said about VMS.

GSK has said it is aiming to make divestments worth about 1 billion pounds ($1.3 billion) in 2019/2020, but McNamara declined to comment on them.

GSK in December announced plans to separate into two companies - one for prescription drugs and vaccines, the other for over-the-counter products - after agreeing the deal with the consumer health business that Pfizer tried, and failed, to sell previously.