Sean Murray and Jeremiah Helm Discuss Recent Fed. Circ. Ruling Affecting Generic Drug Patents in Law360

In the latest installment of Knobbe Martens’ monthly column focused on recent noteworthy Federal Circuit decisions, partners Sean Murray and Jeremiah Helm examine the outcome of Salix Pharmaceuticals v. Norwich Pharmaceuticals.

The Federal Circuit decision in Salix v. Norwich “affirmed in all respects a District of Delaware decision that blocked Norwich's abbreviated new drug application, or ANDA, to sell a generic version of Salix's antibiotic rifaximin,” write Murray and Helm. While Norwich had succeeded in invalidating all of the Salix patents that blocked Norwich from selling generic rifaximin for treatment of irritable bowel syndrome with diarrhea (IBS-D), “in a strange twist, the district court ordered the U.S. Food and Drug Administration not to approve Norwich's ANDA until at least October 2029.”

The authors explain that Norwich’s ANDA also listed a second indication for rifaximin that infringed a second set of Salix patents.   Filing an ANDA listing that infringing indication was an act of infringement even though the ANDA also listed a noninfringing indication. The district court was therefore required to defer approval of the ANDA until the expiration of those other patents.  Even after Norwich amended its ANDA to remove the infringing indication, the possibility remained that drug labelling containing the amended indication might induce physicians to infringe the second set of Salix patents, because that issue was never addressed in the bench trial.  The district court therefore declined to amend its judgment in response to Norwich’s amendment of its ANDA.

Murray and Helm maintain that the outcome in Salix v. Norwich “provides useful lessons for patent practitioners.” They write: “For example, when the seller of a brand-name drug has separate method patents protecting each indication, an ANDA filer should consider whether it makes sense to list each indication in its ANDA. If one indication is protected by patents that are more likely valid and infringed than the patents protecting the other indications, omitting that best-protected indication from the ANDA may be the better part of valor.”

Read the full article here.