In Eurand v. Mylan, No. 2011-1399, -1409 (Federal Circuit, April 16, 2012), the Federal Circuit provided some useful analysis in dealing with hindsight methodology and obvious-to-try theories.

The case involved U.S. Patent Nos. 7,387,793 and 7,544,372 of Aptalis Pharmatech, Inc. (“Aptalis”), directed to extended-release dosage forms of muscle relaxants (cyclobenzaprine hydrochloride).  Anesta AG (“Anesta”), a subsidiary of Cephalon, Inc., is the exclusive licensee of the patents.  The pivotal claim limitation in both patents involved a “therapeutically effective plasma concentration over a period of 24 hours to treat muscle spasm associated with painful musculoskeletal conditions.”  To formulate a muscle relaxant with a therapeutically effective extended-release, a correct pharmacokinetic/pharmacodynamics (“PK/PD”) profile must be obtained, where PK is a quantitative measure of what a person’s body does to the drug and PD is a qualitative assessment of the effect of the drug on the person’s body.

The Defendents in the case, Mylan Pharmaceuticals Inc. and Mylan Inc., and Par Pharmaceutical, filed ANDAs for generic versions of the muscle relaxant.  Aptalis and Anesta filed suit in the U.S. District Court for the District of Delaware, which found both patents invalid as obvious.  Immediate-release cyclobenzaprine formulations were known, but it was undisputed that cyclobenzaprine hydrochloride lacked a known PK/PD relationship at the time the invention was made.  The district court nonetheless found the claims obvious based on the conclusion that the PK profile of the inventive (extended-release) formulation was bioequivalent to the immediate-release formulation.  The district court concluded “[t]hat the lack of a PK/PD relationship is of no moment … given that one of ordinary skill in the art would expect the extended release formulation to have the same PD effect on the body if it has the immediate release formulation’s PK profile.”

On Appeal, the Federal Circuit reversed and vacated the district court’s judgment of invalidity.  It found that the district court had erred when it declared the patents in suit invalid as obvious.  The Federal Circuit noted that the district court’s statement contained an inherent contradiction, since skilled artisans could not conclude that immediate-release and extended-release PK profiles produce the same PD effect because this assumes that a known PK/PD relationship exists.  However, it was undisputed that a PK/PD relationship did not exist, even for the immediate-release formulation.

The Federal Circuit warned against hindsight claims of obviousness and reliance on obvious-to-try theories.

While it may have been obvious to experiment with the use of the same PK profile when contemplating an extended-release formulation, there is nothing to indicate that a skilled artisan would have had a reasonable expectation that such an experiment would succeed in being therapeutically effective.  See Proctor & Gamble, 566 F.3d at 994 (requiring a reasonable expectation of success to prove obviousness).

This distinction is important.  Where a skilled artisan merely pursues “known options” from “a finite number of identified, predictable solutions,” the resulting invention is obvious under Section 103.  KSR, 550 U.S. at 421.  Where, however, a defendant urges an obviousness finding by “merely throw[ing] metaphorical darts at a board” in hopes of arriving at a successful result, but “the prior art gave either no indication of which parameters were critical or no direction as to which of many possible choices is likely to be successful,” courts should reject “hindsight claims of obviousness.”  In re Kubin, 561 F.3d 1351, 1359 (Fed. Cir. 2009) (quoting In re O’Farrell, 853 F.2d 894, 903 (Fed. Cir. 1988)).


Evidence of obviousness, especially when that evidence is proffered in support of an “obvious-to-try” theory, is insufficient unless it indicates that the possible options skilled artisans would have encountered were “finite,” “small,” or “easily traversed,” and that skilled artisans would have had a reason to select the route that produced the claimed invention.  Ortho-McNeil Pharm., Inc. v. Mylan Labs., Inc., 520 F.3d 1358, 1364 (Fed. Cir. 2008) (citing KSR, 550 U.S. at 421).  While it is true that Section 103 bars patentability unless “the improvement is more than the predictable use of prior art elements according to their established functions,” KSR, 550 U.S. at 417, where the prior art, at best, “[gives] only general guidance as to the particular form of the claimed invention or how to achieve it,” relying on an “obvious-to-try” theory to support an obviousness finding is “impermissible.”  In re Kubin, 561 F.3d at 1359 (Quoting In re O’Farrell, 853 F.2d at 903).

Eurand v. Mylan thus provides a current statement by the Federal Circuit on standards of Obviousness relating to hindsight analysis and obvious-to-try situations.

While aspects of the Opinion related to Obviousness have been highlighted above, it also contains guidance on burden shifting with respect to secondary considerations in an Obviousness analysis.  The Opinion further highlights a situation where pre-AIA Best Mode law was applicable because the suit was brought prior to when the Best Mode amendments to the AIA became effective.


-William Reid



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