Sankyo Co. filed a lawsuit Monday against five pharmaceutical companies, demanding they halt sales of generic drugs whose packaging is similar to that of its cholesterol-lowering drug.
Sankyo took the legal step with the Tokyo District Court, claiming the packaging of the five companies' drugs violates fair-trade rules.
The five companies are Taiyo Pharmaceutical Industry Co., Taisho Pharmaceutical Co., Tatsumi Kagaku Co., Kyowa Pharmaceutical Industry Co. and Nichiko Pharmaceutical Co.
The drug whose packaging is allegedly being imitated is Sankyo's Mevalotin, one of the company's best sellers.
Sankyo began marketing Mevalotin in 1989, and the basic patent on it expired last October, unleashing the release of generic versions by about 30 pharmaceutical firms, starting last month.
The drug's domestic sales exceed 100 billion yen a year, accounting for just above 30 percent of Sankyo's drug sales.
Its generic versions are priced about 20 percent lower than Mevalotin.