Case Overview

The Parties

Patents at Issue

This landmark case involved **29 U.S. patents**, a remarkable number even by Hatch-Waxman standards. The portfolio collectively addresses rifaximin’s chemical synthesis, crystalline polymorphs, pharmaceutical formulations, and specific disease-state methods of treatment — a multi-layered exclusivity structure characteristic of aggressive pharmaceutical patent lifecycle management.

• • US4341785 — foundational rifaximin composition patents
• • US7612199 — covering polymorphic forms and formulation innovations
• • US8158644 — directed at therapeutic methods and dosing regimens

The Verdict & Legal Analysis

Outcome

The Federal Circuit’s order was unambiguous: AFFIRMED. The appellate court upheld the lower court’s infringement finding in favor of Salix and co-plaintiffs across the contested patent claims. No damages figure was disclosed in the available case record, which is consistent with Hatch-Waxman proceedings where injunctive relief — blocking generic market entry — is typically the primary remedy rather than monetary damages.

The affirmance effectively prevents Norwich Pharmaceuticals from launching its generic rifaximin 550 mg product until the relevant patents expire or are otherwise invalidated through inter partes review or subsequent litigation.

Key Legal Issues

The case was brought as a patent infringement action under the Hatch-Waxman Act framework, triggered by Norwich’s Paragraph IV certification asserting that Salix’s listed patents were invalid, unenforceable, or would not be infringed by the generic product. With 29 patents in play, the litigation almost certainly required extensive claim construction proceedings, invalidity challenges on grounds including obviousness and anticipation, and detailed technical comparison of Norwich’s ANDA product against the asserted claims.

The Federal Circuit’s affirmance indicates that Norwich failed to persuade either the district court or the appellate panel on validity or non-infringement grounds for the claims necessary to block generic entry. The breadth of the patent portfolio itself is a strategic data point: Salix’s ability to assert patents covering not just the compound but its polymorphic forms, dosing methods, and therapeutic indications created multiple independent barriers for a generic challenger to overcome simultaneously.