Your browser cannot display this PDF inline.
Download the full opinion (PDF)Background
Salix Pharmaceuticals holds patents on Xifaxan (rifaximin), an antibiotic used to treat two distinct conditions: irritable bowel syndrome with diarrhea (IBS-D) and hepatic encephalopathy (HE), a serious brain condition caused by liver disease. Norwich Pharmaceuticals sought to enter the market with a cheaper generic version by filing Abbreviated New Drug Application (ANDA) No. 214369 with the FDA — the standard pathway for generic drugs under the Hatch-Waxman Act.
Salix sued Norwich for patent infringement in the U.S. District Court for the District of Delaware. The Delaware court held that Norwich’s ANDA infringed Salix’s HE-related patents, though it found Salix’s IBS-D patents invalid as obvious. The key remedy: the court entered a final judgment barring the FDA from granting final approval of ANDA No. 214369 until Salix’s HE patents expire in October 2029. Norwich’s request for language carving out an amended application — one that drops the HE indication — was expressly rejected.
Norwich then did exactly what the Delaware court had declined to authorize: it filed an amended version of ANDA No. 214369 removing the hepatic encephalopathy indication, leaving only the IBS-D use. It also moved the Delaware court to modify its judgment under Rule 60(b), arguing the patent judgment’s rationale no longer applied. The Delaware court denied that motion, and the Federal Circuit affirmed, noting the judgment had restricted approval of the entire ANDA number including the non-infringing part. The FDA, following that judgment, granted only tentative approval of Norwich’s amended ANDA — not final approval — declining to act on the IBS-D application until October 2029.
Norwich then filed suit in the U.S. District Court for the District of Columbia, arguing the FDA acted arbitrarily and capriciously by treating the Delaware judgment as applicable to the amended ANDA. The D.C. District Court granted summary judgment for the FDA and Salix, and Norwich appealed to the D.C. Circuit.
The Court’s Holding
The D.C. Circuit affirmed, holding that the FDA correctly read the Delaware court’s final judgment as barring approval of ANDA No. 214369 — by number — until October 2029, regardless of any amendments Norwich made to that application. Writing for the panel, Circuit Judge Walker applied straightforward textual analysis: the Delaware judgment identified the ANDA by its specific number and ordered a delay of its approval. Because “Norwich’s ANDA, even as amended, is still” ANDA 214369, the FDA’s determination tracked the “most straightforward reading of the final judgment.”
The court rejected Norwich’s argument that the judgment implicitly permitted earlier approval of an amended application. The D.C. Circuit pointed to the litigation history in Delaware, where Norwich had asked the district court to include express language allowing the FDA to approve an amended ANDA immediately — and the court twice declined. The court noted that Norwich was now asking the D.C. Circuit to read into the judgment “the qualifying language that the court explicitly declined to include — twice.” Norwich’s own Rule 60(b) briefing confirmed its understanding at the time: it consistently referred to the judgment as blocking approval of its “Amended ANDA.”
The court also distinguished the earlier Federal Circuit decision in Ferring B.V. v. Watson Laboratories, 764 F.3d 1382 (Fed. Cir. 2014), which had treated an original ANDA and an amended ANDA differently — but only because, in that case, the defendant had promised during trial to amend its application, a circumstance absent here.
Key Takeaways
- Amended ANDAs don’t escape a patent judgment. When a Delaware patent court bars FDA approval of a specific ANDA number, amending that ANDA does not create a new, unencumbered application. The judgment runs to the application number itself.
- Courts take their own judgments seriously. The Delaware District Court specifically rejected Norwich’s request to carve out amended applications from its judgment — twice. The D.C. Circuit refused to grant through statutory interpretation what Norwich had failed to obtain in the original litigation.
- Post-judgment ANDA amendments are a losing strategy. Generic applicants cannot rely on post-judgment application modifications to circumvent Hatch-Waxman exclusivity periods. If amendments could moot a patent judgment, it would undermine the finality of Hatch-Waxman litigation outcomes.
- FDA deference to patent court judgments is proper. The FDA does not independently interpret the scope of patent rights — it follows judicial orders. The D.C. Circuit confirmed that deference to the patent court’s judgment was correct, not arbitrary.
Why It Matters
The Hatch-Waxman Act is the legal framework that governs how generic drugs reach the market. It creates a structured litigation pathway: brand-name manufacturers can sue generic challengers before any drug is sold, and courts can bar FDA approval if infringement is found. For generic drug companies, an adverse Hatch-Waxman judgment can mean years of delay while brand-name exclusivity continues. Norwich’s case illustrated what seemed like an intuitive workaround — if you drop the infringing use from your label, shouldn’t the patent bar go away? The D.C. Circuit firmly closed that door.
The ruling reinforces that Hatch-Waxman patent judgments have teeth: they bind the specific ANDA that was litigated, and clever post-judgment maneuvering — such as label amendments or Rule 60(b) motions — won’t reverse an adverse outcome without a genuine change in the underlying legal posture (like patent invalidation). Pharmaceutical companies and their counsel should factor this rigidity into strategy well before trial, because the judgment’s scope is largely locked at entry. For Salix, this decision secures its market exclusivity over Xifaxan through October 2029. For patients, cheaper generic alternatives remain unavailable for another three-plus years.