The deal, which also involves the payment of 1.38bn to joint venture partner Shin Nihon Jitsugyo, is being seen as part of a move to reverse the British group's relative underperformance in Japan.
A Glaxo spokesman said taking 100 per cent control of the joint venture "gives us a clearer, simpler structure to grow the business."
It is the last big step in rationalising the separate Glaxo and Wellcome businesses, which previously operated side by side in many of the world's main drug markets following last year's merger.
Once fully owned, it is expected that Nippon Glaxo will be merged with Nippon Wellcome, the 55 per cent owned joint venture with Sumitomo Chemical Company which came with Wellcome. Glaxo said it had "no immediate plans" to merge the two companies.Reuse content