A Delaware federal judge on Oct. 7 upheld Endo Pharmaceuticals Inc.’s patent for its opioid painkiller Opana ER, rejecting arguments by Amneal Pharmaceuticals and Teva Pharmaceuticals USA that the patent claim was invalid as obvious and that Teva had obtained permission to use its active ingredient.
In a 30-page trial opinion, U.S. District Judge Richard G. Andrews of the District of Delaware on Oct. 7 ruled that nothing in the prior art had taught how to manufacture oxymorphone with low levels of alpha, beta-unsaturated ketone, or ABUK, a compound that was discovered in 2002 to be linked to cancer.
