Background
Salix Pharmaceuticals holds patents for the drug Xifaxan, used to treat hepatic encephalopathy and irritable bowel syndrome. Norwich Pharmaceuticals sought to market a generic version via an Abbreviated New Drug Application, numbered 214369. A Delaware district court found that the generic application infringed Salix’s patents for hepatic encephalopathy but was invalid for other indications. The court issued a final judgment delaying FDA approval of the specific application number until Salix’s patents expire in October 2029. Norwich later amended its application to remove the hepatic encephalopathy indication and sought immediate approval, arguing the delay was no longer necessary. The FDA denied final approval, citing the existing judgment, and the district court granted summary judgment to the FDA and Salix.
The court’s reasoning
The court analyzed the plain meaning of the Delaware district court’s final judgment, which explicitly referenced the specific application number 214369 and ordered a delay until patent expiration. The court found that the judgment did not distinguish between the original and amended versions of the application. The court noted that Norwich had previously argued for language excluding amended applications but was rejected by the district court. The court also distinguished the case from Ferring B.V. v. Watson Laboratories, noting that in this instance, the applicant litigated through trial based on a specific application and then attempted to change it post-judgment. The court concluded that the FDA correctly interpreted the judgment to bar approval of the amended application until the specified date.
What it means going forward
Generic drug manufacturers must adhere to the specific application numbers and terms set forth in final patent infringement judgments, even if they modify their applications to remove infringing indications after the judgment is entered.