Daiichi Sankyo, which was created through a merger in 2005, incurred a net loss of 297.8 billion yen in April-December, compared with a 96.42 billion yen profit a year ago.

For the full year to March, the company now forecasts a net loss of 316 billion yen, its first annual loss, compared with the previous estimate of a 65 billion yen profit.

The company, however, kept unchanged its plan to pay its dividend of 80 yen per share for the full year, up from 70 yen last year.

The loss forecast compares with an average forecast for a 280.4 billion yen loss from seven analysts polled by Reuters Estimates.

Daiichi Sankyo bought a controlling 63.9 per cent stake in Ranbaxy, a major generic drugmaker, last year for nearly 500 billion yen to diversify its revenue base.

Japanese drugmakers, like their global rivals, are seeking to head off large drops in revenue after patent expirations on key drugs with acquisitions and partnership deals.