Japan's top drugmaker Takeda Pharmaceutical Co <4502.T> posted a 17 percent fall in second-quarter operating profit, hurt by currency losses and worries over calls for new warnings on its top-selling diabetes pill Actos.

The company also slashed its full-year outlook by more than 40 percent to take into account changes in foreign exchange rate forecasts and its $13.7 billion purchase of Swiss drugmaker Nycomed earlier this year.

Like many other Japanese companies, Takeda's profits are dented by a strong yen, while a request by European authorities to add warnings of possible link to bladder cancer to Actos pills weighed on the drug's sales.

Takeda, which generates nearly half of its sales outside Japan, has been grappling with a dollar that has weakened to record lows recently and remains below 80 yen, even after Japan's latest intervention earlier this week.

The company, which ranks ahead of Astellas Pharma <4503.T>, Otsuka Holdings Co <4578.T> and Daiichi Sankyo Co <4568.T> in terms of market value in Japan, booked a July-September operating profit of 94.9 billion yen ($1.2 billion).

Takeda got some help from a domestic sales growth of recently released treatments such as diabetes drug Nesina and cancer drug Vectibex to help boost revenue.

Takeda, nearly 30 percent owned by foreign investors, cut its operating-profit forecast for the business year to end-March 2012 to 270 billion yen from its initial estimate of 390 billion yen.

That compares with the average estimate of 388.1 billion yen from 17 analysts polled by Thomson Reuters I/B/E/S.

Shares of Takeda have fallen about 13 percent since the start of the calendar year, compared with a more than 14 percent drop in the benchmark Nikkei average <.N225>. They closed 0.9 percent higher before the results on Friday.

($1 = 77.980 Japanese Yen)

(Reporting by James Topham; Editing by Vinu Pilakkott)