Shire plc’s subsidiary Shire LLC has filed a lawsuit in the
U.S. District Court for the Northern District of California against Impax
Laboratories, Inc. and Watson Pharmaceuticals, Inc., Watson Laboratories,
Inc.-Florida, Watson Pharma, Inc and ANDA, Inc. for the infringement of U.S.
Patent Nos. 5,854,290 (the ‘290 patent), 6,287,599 (the ‘599 patent), and
6,811,794 (the ‘794 patent).

The lawsuit results from Abbreviated New Drug Applications
(ANDAs) filed by Impax and Watson for generic versions of 4 mg guanfacine hydrochloride
extended release tablets, INTUNIV(TM), which seek to market such generic
products before the expiration of the ‘290, ‘599, and ‘794 patents. The
regulatory exclusivity period for INTUNIV(TM) runs through September 2, 2012.