The U.S. Court of Appeals for the Federal Circuit recently affirmed a district court’s grant of summary judgment of non-infringement based on a claim interpretation of “about” in reference to a numerical ratio. Ortho-McNeil Pharm. Inc. v. Caraco Pharm. Labs., Ltd., Case No. 06-1102 (Fed. Cir., Jan. 19, 2007) (McKinney, C.J. of S.D. Ind., by designation).

Ortho-McNeil Pharmaceutical, Inc. owns a patent that relates to a pharmaceutical composition comprising certain weight ratios of the analgesics tramadol and acetaminophen marketed as Ultracet®. Ortho filed suit after Caraco filed an Abbreviated New Drug Application (ANDA) for a generic version of Ultracet®, which included a paragraph IV certification with respect to the Ortho patent. Caraco’s ANDA requested approval for a formulation containing tramadol and acetaminophen with an average weight ratio of tramadol to acetaminophen of 1:8.67 and requiring a weight ratio of no less than 1:7.5. Ortho alleged that Caraco’s proposed formulation infringed claim 6 of the its patent, which is directed to “a pharmaceutical composition comprising a tramadol material and acetaminophen, wherein the ratio of the tramadol material to acetaminophen is a weight ratio of about 1:5.”

The only claim construction dispute between the parties was the meaning of the phrase “about 1:5.” The term “about” is used in all of the claims of the patent to modify the weight ratios claimed therein. Caraco argued that the proper construction of “about 1.5” was “approximately 1:5, subject perhaps to minor measuring errors of, say, 5 or 10%.” Ortho argued that the proper construction is “approximately 1:5, and … encompasses a range of ratios of at least 1:3.6 to 1:7.1.” On Caraco’s motion for summary judgment of no infringement, the district court essentially followed Ortho's claim construction, but found that Caraco’s ANDA formulation did not literally infringe Ortho patent (the ’691 patent). Invoking the doctrine of claim vitiation, the district court also found no infringement under the doctrine of equivalents. The district court concluded that finding infringement by Caraco’s formulation with an average weight ratio of 1:8.67 would render meaningless the “about 1:5” limitation. Ortho appealed.

Commencing its review with claim construction, the Federal Circuit relied on intrinsic and extrinsic evidence to determine that the district court had not erred in construing the term “about 1:5” to mean “approximately 1:5, encompassing a range of ratios no greater than 1:3.6 to 1:7.1.” In reaching this determination, the Federal Circuit noted that “[t]he intrinsic evidence points to a meaning for the term ‘about 1:5’ that is narrow because the 1:5 weight ratio, along with the 1:1 weight ratio, is distinctly claimed and distinguished from other broader weight ratios in the patent.” In particular, the Court noted that, because some of the claims in Ortho’s patent recite a single weight ratio and some claims recite ranges of weight ratios, “one of ordinary skill in the art would understand the inventors intended a range when they claimed one and something more precise when they did not.”

With regard to the district court’s decision to grant summary judgment of non-infringement, the Federal Circuit first determined that under the proper claim construction, “there can be no literal infringement because Caraco’s formulation must have a weight ratio of tramadol to acetaminophen of no less than 1:7.5.” Then, turning to the issue of infringement under the doctrine of equivalents, the Federal Circuit agreed with the district court that to expand the weight ratio of “about 1:5” to encompass a composition having an average weight ratio of 1:8.76 “would eviscerate the limitation.”