## Facts

- Daiichi owned U.S. Patent No. 5,401,741, claiming a method of treating bacterial ear infections (“otopathy”) by topically administering ofloxacin (or a salt) in a pharmaceutically acceptable carrier.
- Apotex filed an ANDA seeking approval to market a generic ofloxacin otic solution and certified under Paragraph IV that the patent was invalid and/or not infringed.
- Daiichi sued Apotex for infringement under the Hatch–Waxman Act in the District of New Jersey.
- The district court construed “effective to treat” to mean “efficacious and safe.”
- The inventors included individuals with backgrounds in otolaryngology, clinical development, and antibiotic research; their work included testing ofloxacin for otic safety (including ototoxicity concerns).
- After a bench trial, the district court defined the person having ordinary skill in the art (PHOSITA) as a medical doctor experienced in treating ear infections and held the patent not obvious; infringement was effectively resolved by Apotex’s stipulation under the court’s construction.
- Apotex appealed the PHOSITA definition and the resulting nonobviousness determination.

## Issues

1. Whether the district court erred by defining the PHOSITA as a treating physician rather than someone skilled in pharmaceutical science and antibiotic drug development relevant to topical otic formulations.
2. Whether, under the correct PHOSITA and in view of the prior art, the claimed method of treating ear infections with topical ofloxacin would have been obvious.

## Decision

- The Federal Circuit reversed the district court’s judgment.
- The court held the district court used an incorrect PHOSITA framework by focusing on clinicians rather than the technical field of the invention (pharmaceutical development and otic formulation/safety).
- Applying the correct PHOSITA, the court concluded the claimed method would have been obvious in light of the prior art, including teachings about ofloxacin/fluoroquinolones and otic safety considerations.
- Because the patent was invalid for obviousness, the infringement judgment could not stand.

## Legal Principles

- Obviousness is a question of law based on underlying factual findings, including the scope/content of the prior art and the level of ordinary skill in the art.
- The PHOSITA is a hypothetical person presumed aware of pertinent prior art; the relevant field is identified by the patent’s subject matter and the prior art, not by the profession of end-users of the invention.
- In pharmaceutical cases, claims directed to selecting/formulating a known compound for a predictable use may be obvious where the prior art supplies a reason to pursue the approach and a reasonable expectation of success.
- Objective indicia (e.g., commercial success) may be considered but do not overcome a strong showing of obviousness absent a meaningful nexus to the claimed invention.

## Conclusion

The Federal Circuit invalidated Daiichi’s method patent as obvious after correcting the PHOSITA from a treating physician to a pharmaceutical drug-development professional, concluding that prior art would have motivated topical otic use of ofloxacin with a reasonable expectation of success.


Daiichi Sankyo Co. v. Apotex, Inc., 501 F.3d 1254 (Fed. Cir. 2007)