Astellas Pharma Inc. (headquarters: Tokyo; President and CEO: Toichi Takenaka; "Astellas") and Boehringer Ingelheim Pharmaceuticals, Inc. ("BIPI"), a US subsidiary of Boehringer Ingelheim of Germany, jointly filed a patent infringement lawsuit in the United States against Ranbaxy Inc., Ranbaxy Pharmaceuticals Inc., Ranbaxy Laboratories Inc. (collectively, "Ranbaxy") regarding its submission of an abbreviated new drug application (ANDA) for a generic version of Astellas' drug product, sold under the trademark Flomax® (generic name: tamsulosin HCl; brand name in Japan: Harnal®) , which is used for the treatment of benign prostatic hyperplasia. The patent infringement action was filed at the US Federal District Court in New Jersey on May 13th, 2005 requesting, among others, an order that date of approval of Ranbaxy's ANDA be not earlier than the expiration on October 27, 2009 of Astellas' US Patent No. 4,703,063 on tamsulosin HCl, or any later date of exclusivity Astellas and BIPI are or become entitled.

Tamsulosin HCl was invented by Astellas and has been marketed in 64 countries since it was launched in Japan in 1993. In the US, under a license from Astellas, BIPI has been marketing the product since 1997 under the brand name of Flomax®. Since October 2004, Astellas Pharma US, Inc., a US subsidiary of Astellas, has been copromoting the product with BIPI.

Astellas believes that the said patent on tamsulosin HCl is valid and intends to enforce it against infringement.