The Court of Appeals for the Federal Circuit upheld the ruling of a federal court that its generic version of painkiller Ultracet does not infringe upon Ortho-McNeil’s patent. (Ortho-McNeil Pharmaceutical, Inc. v. Caraco Pharmaceutical Laboratories; 06-1102). 

Caraco’s Abbreviated New Drug Application was to make and sell a pharmaceutical composition containing tramadol and acetaminophen with an average weight ratio of tramadol to acetaminophen of 1:8.67. Caraco’s ANDA also expressly requires Caraco’s formulation to have a weight ratio of no less than 1:7.5.1

In response to Caraco’s ANDA, Ortho alleged that Caraco infringed claim 6 of the ‘691 patent. After Ortho sued for patent infringement, Ortho appealed the granting of Caraco’s motion for summary judgment of non-infringement regarding claim 6 of U.S. Patent No. 5,336,691. The ‘691 patent has fifteen claims directed to a pharmaceutical composition comprising certain weight ratios of two known drugs, tramadol and acetaminophen. Both of these drugs act as pain relievers, i.e., analgesics. The ‘691 patent discloses that where these components are in certain ratios the pharmacological effects of the compositions are superadditive or synergistic. More specifically, the description of the invention reads:

The [acetaminophen] and the tramadol material are generally present in a weight ratio of tramadol material to [acetaminophen] from about 1:1 to 1:1600. Certain ratios result in a composition which exhibits synergistic analgesic effects. For example, in a composition comprising a tramadol material and [acetaminophen], the ratio of the tramadol material: [acetaminophen] is preferably from about 1:5 to 1:1600; and, more preferably, from about 1:19 to 1:800.

The most preferred ratios are from about 1:19 to 1:50. Compositions of a tramadol material and [acetaminophen] within these weight ratios have been shown to exhibit synergistic analgesic effects. In addition, the particular compositions wherein the ratio of the components are [sic] about 1:1 and about 1:5 are encompassed by the present invention.

Claim 6 reads:

[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.” Caraco argued that the proper construction is “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.”

Under either claim construction, Caraco argued its ANDA-defined product did not literally infringe. With respect to infringement under the doctrine of equivalents, Caraco argued that the doctrine should not apply to broaden the scope of the “about 1:5” limitation beyond the range of ratios suggested by the confidence intervals in the patent because to do so would, alternatively, improperly expand a narrow claim limitation, improperly eliminate the 1:5 claim limitation, or improperly encompass the prior art disclosed in U.S. Patent No. 3,652,589 to Flick, et al.

Caraco also stated that prosecution history estoppel should apply because, during reissue proceedings relating to the ‘691 patent, Ortho narrowed the “about 1:5” limitation to something very close to 1:5 when Ortho described the 1:5 limitation and clearly distinguished it from the 1:10 limitation disclosed in the Flick patent.

Ortho argued that, under its construction, there were issues of fact as to literal infringement. In addition, Ortho contended that its experts would opine that, under the function-way-result test, Caraco’s product with a tramadol to acetaminophen average weight ratio of 1:8.67 was indistinguishable from that with a ratio of 1:5.

The district court construed the “about 1:5” limitation of claim 6 to mean “approximately 1:5, encompassing a range of ratios no greater than 1:3.6 to 1:7.1” based on reissue proceedings where Ortho distinguished the “about 1:5” limitation of claim 6.

The court noted that the word “about” does not have a universal meaning in patent claims, the meaning depends upon the technological facts of the particular case, stating:

The use of the word “about,” avoids a strict numerical boundary to the specified parameter. Its range must be interpreted in its technological and stylistic context. We thus consider how the term . . . was used in the patent specification, the prosecution history, and other claims. It is appropriate to consider the effects of varying that parameter, for the inventor’s intended meaning is relevant. Extrinsic evidence of meaning and usage in the art may be helpful in determining the criticality of the parameter.

The court held: 

We must focus, then, on the criticality of the 1:5 ratio to the invention in claim 6 of the ‘691 patent. The 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 ratio ranges in the patent. There are fifteen claims in the ‘691 patent, all of which use the term “about” to modify the weight ratio or weight ratio ranges of tramadol to acetaminophen. There are two claims, claim 4 and disputed claim 6, that claim a single weight ratio; the other claims distinctly point out ranges of weight ratios. For example, independent claim 1 reads: “A pharmaceutical composition comprising a tramadol material and acetaminophen, wherein the ratio of the tramadol material to acetaminophen is a weight ratio from about 1:1 to about 1:1600.” Id. col.11 ll.19-22. This leads to a conclusion that 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.

Considering the intrinsic and extrinsic evidence in this case, we see no error in the district court’s construction of 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.”




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