ASTRAZENECA AB v. MYLAN PHARMACEUTICALS INC.

Before:  Taranto, Hughes, and Stoll

Summary:  For purposes of claim construction, intrinsic evidence can trump the plain and ordinary meaning of scientific conventions such as significant figures.  

AstraZeneca AB and AstraZeneca Pharmaceuticals LP (collectively, “AstraZeneca”) sued Mylan Pharmaceuticals Inc. and Kindeva Drug Delivery L.P. (collectively, “Mylan”) for infringement of patents directed to a pressurized metered-dose inhaler that administers a stable formoterol/budesonide pharmaceutical.  The district court construed the term “0.001%” in the limitation “PVP K25 is present at a concentration of 0.001% w/w” according to its “plain and ordinary meaning, that is, expressed with one significant digit” (i.e., encompassing a concentration of PVP K25 in the range of 0.0005% to 0.0014%).  Mylan then stipulated to infringement and the district court entered final judgment of infringement.   

The Federal Circuit held the district court erred in its claim construction and vacated and remanded the infringement holding.  The Federal Circuit stated that while the plain and ordinary meaning was based on scientific convention, the intrinsic evidence (i.e., written description and prosecution history) placed considerable emphasis on formulation stability and thus supported the narrower construction of “‘0.001%’ as [a] precise number, with only minor variations, i.e., 0.00095% to 0.00104%.” For example, the written description showed the inventors understood that a formulation comprising 0.001% w/w PVP K25 is more stable than a formulation with even a slight difference in the concentration (e.g., 0.0005% w/w PVP K25).  Furthermore, over the course of the prosecution history, the patentees narrowed the concentration of PVP K25 to 0.001% w/w from a broader range without using the qualifier “about” in order to “emphasiz[e] to the Examiner that 0.001% w/w PVP K25—not concentrations slightly more or less than 0.001% w/w—was critical to stability of the formulation.”

Judge Taranto dissented in part, arguing that, “0.001%” should be construed to have its significant figure meaning with one “possible interval-shrinking change” that ultimately would not disturb the previous finding of infringement.