Jan. 25--TOKYO -- Dainippon Sumitomo Pharma Co. said Wednesday that Pfizer Ltd. has filed a lawsuit against it and its parent firm Sumitomo Chemical Co. with a British court. Pfizer is calling on both firms to return all data concerning a hypertension drug licensed by the U.S. firm and demanding cessation of its production and marketing by Dainippon, the Japanese drugmaker said.
