Dainippon Sumitomo and its parent company Sumitomo Chemical yesterday said that they have reached a settlement agreement with US drug giant Pfizer for the high blood pressure and angina drug Amlodin (amlodipine).

The suits were brought by Pfizer against the two Japanese firms - in both Japan and England - following the merger of Dainippon Pharmaceutical and Sumitomo in 2005, saying that the license agreements for Sumitomo to sell Amlodin had expired because of the marriage union and, therefore, it would be seeking damages for patent infringement as well as the immediate withdrawal of all products from the market.

In retaliation, Dainippon Sumitomo filed suit arguing that Pfizer had "no justifiable grounds" for seeking an injunction against the manufacture and sale of the drug, which is the Japanese firm's biggest-selling offering, pulling in almost $500 million annually.

The firms have now agreed to drop all lawsuits and to resume their license agreement, which was originally signed in 1991, on the same terms as before. The settlement will not involve any payments to either Pfizer or Dainippon Sumitomo.