Collegium Pharmaceutical Inc. filed a lawsuit in the U.S. District Court for the District of Delaware alleging patent infringement by a Teva Pharmaceutical Industries Ltd. unit for extended-release capsules of opioid painkiller Xtampza.

The Teva unit, Teva Pharmaceuticals USA Inc., had filed an Abbreviated New Drug Application, or ANDA, with the U.S. Food and Drug Administration seeking approval for a generic version of Xtampza, or oxycodone. As part of the ANDA process, the U.S. unit of the Israel-based generic maker needed to certify that its product does not infringe the approved drug's listed patents, or that such patents are invalid.

The Teva unit sent a certification to Collegium stating the 11 patents on the drug held by the specialty company are "invalid, unenforceable, and/or will not be infringed by Teva's proposed product," Collegium said in an SEC filing. In response to this claim, the Canton, Mass.-based specialty pharmaceutical filed the lawsuit under the Hatch-Waxman Act against Teva.