Federal Circuit Affirms No Infringement in Pharmaceutical Patent Dispute Over pH Measurement Conditions For Epoprostenol Composition

Why It Matters

The ruling clarifies how quantitative patent limits must be tied to explicit measurement conditions, shaping future pharma patent drafting and generic drug litigation strategies.

Key Takeaways

• Federal Circuit requires standard‑temperature pH measurement for claim construction
• Plaintiff’s equivalents theory blocked by prosecution‑history estoppel
• Disclosure‑dedication rule bars recapturing unclaimed pH ranges
• Generic maker avoided infringement by measuring pH at 25 °C
• Patent drafts should tie claim language to explicit measurement conditions

Pulse Analysis

The Federal Circuit’s May 13 decision in Actelion v. Mylan clarifies how courts will interpret quantitative claim limitations that lack explicit measurement conditions. By anchoring the phrase “pH of 13 or higher” to the USP‑prescribed standard temperature of 25 ± 2 °C, the court rejected the defendant’s argument that refrigerated‑process temperatures could satisfy the limitation. This construction directly influences the viability of abbreviated new drug applications, because generic manufacturers can now rely on a predictable benchmark when assessing potential infringement of stability‑related patents.

Beyond literal infringement, the panel applied two well‑established defenses to shut down the plaintiff’s equivalents theory. First, prosecution‑history estoppel barred recapturing pH values below the narrowed “13 or higher” limitation, since the claim was amended to overcome an obviousness rejection. Second, the disclosure‑dedication rule deemed the specification’s lower‑pH ranges as dedicated to the public, preventing the patentee from later asserting them as equivalents. Together, these doctrines reinforce the principle that any narrowing amendment or explicit alternative disclosed during prosecution can foreclose broader infringement arguments.

For pharmaceutical innovators, the ruling sends a clear signal: claim language must be paired with precise, reproducible measurement parameters, and any disclosed alternatives should be carefully considered before filing. Drafting patents that leave temperature or pH conditions ambiguous can invite costly litigation over claim construction, while overly narrow claims risk being easily designed around by generics. Companies are therefore incentivized to include explicit testing conditions in both the specification and the claims, and to avoid narrowing amendments that could trigger estoppel. This decision will likely shape future patent strategies across the biotech sector, where stability metrics are often central to product protection.