Background
Daiichi Sankyo held a patent on an otic (ear drop) formulation of ofloxacin, a fluoroquinolone antibiotic, for treating ear infections without anesthesia — the claimed formulation was pH-adjusted to reduce the pain caused by instilling drops into the ear canal. The drug (marketed as Floxin Otic) was widely prescribed for otitis media and otitis externa in children. Apotex filed an ANDA to market a generic ofloxacin otic formulation and Daiichi filed a Hatch-Waxman patent infringement suit.
The district court found the patent obvious, reasoning that a formulation scientist (the court’s definition of a person of ordinary skill in the art) would have known to adjust the pH of an antibiotic solution to reduce instillation pain. Daiichi appealed, arguing that the court had defined the relevant ordinary skill level too broadly — the proper person of ordinary skill was a medical doctor specializing in ear treatments, not a pharmaceutical formulation scientist, and that a physician would not have had the specific formulation expertise to arrive at the claimed pH-adjusted otic formulation.
The Court’s Holding
The Federal Circuit reversed the obviousness finding and remanded. The court held that the district court had defined ordinary skill in the art too broadly. In pharmaceutical patent cases, the person of ordinary skill is typically defined by reference to the field of the invention as claimed — here, the invention was an otic pharmaceutical formulation for use in medical treatment, and the relevant practitioner was a specialist physician (otolaryngologist) with clinical knowledge of ear treatment, not a generic pharmaceutical formulation scientist. A treating physician might know that pH affected patient comfort, but would lack the specialized formulation expertise to design a specific pH-adjusted antibiotic preparation for the ear canal.
With the correct ordinary skill level defined, the court found the obviousness analysis needed to be reconsidered: the district court’s analysis had improperly assumed a level of formulation expertise that the properly defined skilled artisan would not possess. The case was remanded for the district court to redo the analysis under the correct definition of ordinary skill.
Key Takeaways
- The level of ordinary skill in the art is a critical legal question that must be carefully defined in the context of the specific invention — and it can be outcome-determinative in obviousness analysis, because the motivation to combine prior art elements and the predictability of results both depend on what the skilled artisan would know and be able to do.
- A pharmaceutical practitioner (treating physician) and a pharmaceutical formulation scientist have very different skill sets, and the choice between them can determine whether a pharmaceutical claim is obvious or non-obvious over the prior art.
- Courts must be careful not to define the person of ordinary skill at too high a level — attributing expertise that the relevant practitioners would not actually have — because this can unfairly render non-obvious inventions obvious.
- Pharmaceutical and biotech litigants should devote significant effort to establishing the correct level of ordinary skill through expert testimony and clear evidence about the educational background and practical expertise of practitioners in the relevant field.
Why It Matters
Daiichi Sankyo v. Apotex illustrated that seemingly technical procedural decisions — specifically, how to define the level of ordinary skill in the art — can be the central determinant of whether a pharmaceutical patent survives an obviousness challenge. The ruling reinforced that ordinary skill is a field-specific, contextual determination that requires careful analysis of who actually practices in the relevant area of medicine or science.
For pharmaceutical patent litigants, the case underscored the importance of fighting hard over the ordinary skill definition at trial, and of presenting expert witnesses whose backgrounds match the correctly defined level of skill. A formulation expert who overstates their peers’ knowledge, or a physician witness who underestimates what treating doctors would know, can skew the entire obviousness analysis. Getting ordinary skill right is often the key to winning or losing a Hatch-Waxman validity trial.