Somaxon Pharmaceuticals Inc. (SOMX) disclosed it filed a patent-infringement lawsuit against Par Pharmaceutical Inc. (PRX), following Par's request for approval to market generic versions of sleep aid Silenor in the U.S.
The suit is Somaxon's latest against a generic applicant for Silenor, its first product on the market. In February, it filed a separate lawsuit against Par that involved a different patent also related to Silenor. It has also engaged in litigation with companies such as Mylan Inc. (MYL).
Par couldn't immediately be reached for comment.
Somaxon reported earlier this month its first-quarter loss widened sharply on higher costs, though it reported product sales, of which it had none a year earlier.
Somaxon's shares closed down Friday at $2.35, while Par finished higher at $33.62. Neither was active after-hours.
-By Matt Jarzemsky, Dow Jones Newswires; 212-416-2240; firstname.lastname@example.org