OTSUKA AMERICA PHARMACEUTICAL, INC. v. HETERO LABS LIMITED
Authored by: Jeremy J. Gustrowky
The Federal Circuit has affirmed a preliminary injunction preventing Hetero Labs Limited from launching a generic version of Nuedexta, a drug used to treat pseudobulbar affect and emotional lability in patients with neurological conditions. However, the court vacated the district court’s decision to waive the bond requirement typically required when a preliminary injunction issues, sending that issue back for reconsideration.
The case centered on how to interpret the terms “dextromethorphan” and “quinidine” in claim 1 of U.S. Patent No. 7,659,282, owned by Avanir Pharmaceuticals (a subsidiary of Otsuka America Pharmaceutical). The patent covers a method of administering these two drugs together, with dextromethorphan providing the therapeutic effect and quinidine slowing its metabolism in the liver. Claim 1 requires a weight-to-weight ratio of dextromethorphan to quinidine of “1:0.5 or less.” The dispute turned on whether that ratio should be calculated using only the weight of the active drug molecules (the “free base” forms) or the full weight of the salt compounds actually administered, which include additional non-therapeutic ions.
Hetero argued that the ratio should be measured using only the active moiety weights. Under that interpretation, its generic product, containing 20 mg of dextromethorphan hydrobromide and 10 mg of quinidine sulfate, would yield a ratio of 1:0.56, falling outside the claimed range. Notably, Otsuka’s own Nuedexta product would also fall outside the claim under Hetero’s construction, a point the majority found highly probative. The court reasoned it was “highly improbable” that the patentee would have drafted claims that excluded the very product the patent was meant to protect.
Writing for the majority, Judge Bryson found that the specification, dependent claims, and prosecution history all supported reading “dextromethorphan” and “quinidine” to include their salt forms, with the weight-to-weight ratio calculated based on the form actually administered. The court pointed to dependent claims explicitly covering salt forms, specification passages using the terms as shorthand for salt-form doses in clinical studies, and examiner statements during prosecution treating “quinidine” as including “quinidine sulfate.” The court also rejected Hetero’s indefiniteness argument, explaining that for any given formulation, the ratio calculation is straightforward.
Judge Dyk dissented on claim construction, arguing that the purpose of the invention (reducing quinidine blood levels while maintaining effective dextromethorphan levels) only makes sense if the ratio is measured based on the active moieties. He noted that salts dilute the active compounds in different proportions, so comparing salt weights distorts the meaningful relationship between the therapeutic components. He would have reversed the preliminary injunction.
On the bond issue, the Federal Circuit applied Third Circuit law, which treats the Rule 65(c) bond requirement as “almost mandatory” and permits waiver only in narrow circumstances. The district court had waived the bond based on concerns about a “chilling effect on access to justice” from a multi-million-dollar bond. But because Hetero’s planned generic launch was clearly a commercial, money-making activity, and the Third Circuit has never excused a bond in such circumstances, the Federal Circuit vacated the waiver and remanded for the district court to set an appropriate bond amount, particularly given that the ‘282 patent expires in August 2026.