Our Bureau

New Delhi , May 16

TOKYO-based Astellas Pharma Inc and Boehringer Ingelheim Pharmaceuticals Inc (BIPI), the US subsidiary of Boehringer Ingelheim of Germany, have jointly filed a patent infringement lawsuit in the US against Indian pharmaceutical major Ranbaxy Laboratories regarding its submission of an abbreviated new drug application (ANDA) for the generic version of a drug used to treat benign prostatic hyperplasia (enlargement of the prostrate glands).

A press release posted on Astellas' Web site says, "The patent infringement action was filed at the US Federal District Court in New Jersey on May 13, 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 licence from Astellas, BIPI has been marketing it since 1997 under the brand name Flomax. Since October 2004, Astellas Pharma US Inc has been co-promoting the product with BIPI.

"Astellas believes that the said patent on Tamsulosin HCl is valid and intends to enforce it against infringement," the Web site said.