At a time when AstraZeneca is bracing itself to deal with generic competition to Nexium elsewhere, the company has boosted by Japanese approval for the proton pump inhibitor blockbuster.

The Japanese Ministry of Health, Labour and Welfare has given the green light to Nexium (esomeprazole) for the treatment of acid-related diseases, as well as the prevention of recurrence of gastric ulcer and duodenal ulcer in patients treated with non-steroidal anti-inflammatory drugs. The approval is based on eight clinical studies conducted in Japan, including two large trials of patients with reflux oesophagitis and two other studies in patients taking NSAIDs.

Nexium will be co-promoted in Japan with Daiichi Sankyo which will be responsible for distribution while AstraZeneca will manufacture and develop the product. The Anglo-Swedish drugmaker notes that the PPI market in Japan in 2010 was worth $2 billion.

Tony Zook, head of AstraZeneca’s global commercial organisation, said "we are pleased to be able to add Nexium to our portfolio of medicines in Japan, our second largest market, and strengthen our leadership in the global gastrointestinal sector.” Revenues there grew 4% in 2010 to around $2.62 billion in 2010 and the company has around 3,100 employees in Japan, plus an R&D centre in Osaka.

The Japanese approval for Nexium comes a fortnight after the loss of a key patent covering the drug in Europe. Generics are likely to be launched by the end of the year which will eat into Nexium's considerable sales; they reached $4.97 billion in 2010, and some $1.20 billion of that came from Europe.