Carlson Caspers successfully defended an indefiniteness verdict at the Federal Circuit in Forest Laboratories, Inc. v. Teva Pharmaceuticals USA, Inc.  The asserted claims were directed to extended-release formulations of memantine, and were listed in the Orange Book for Forest’s Namenda XR® product.  The applicants chose to define their formulation based on pharmacokinetic principles rather than the excipients used to prepare the formulation.  Specifically, the claims required a comparison of the plasma profile yielded by administration of an extended-release dosage form to the plasma profile yielded by administration of an immediate release dosage form.  Pharmacokinetic tests like this are highly dependent on the study design, however, and the specification lacked meaningful guidance about the test method to be used.  Accordingly, the Federal Circuit affirmed the indefiniteness verdict.  (“[T]he district court’s indefiniteness ruling is supported by precedents that hold claims indefinite . . . where the claims require measured quantities (absolute or relative), different  techniques for such measurements are known in the art and some produce infringing results and others not, the intrinsic evidence does not adequately specify the technique or techniques to use, and extrinsic evidence does not show that a relevant skilled artisan would know what technique or techniques to use.”)

But Judge Lourie did not stop there.  He offered a concurring opinion suggesting the claims were indefinite for a much more fundamental reason:

Pharmaceutical dosage forms containing memantine are old.  This claim attempts to encompass an extended release formulation of memantine, but it does so without including any materials that cause the extended release.  It attempts to serve that function by defining a result, a concentration profile.  Claiming a result without reciting what materials produce that result is the epitome of an indefinite claim.  Such a claim fails to delineate with any reasonable certainty the requirements of the formulation. . . .  It is a hollow claim.

Judge Lourie’s statement raises concerns with the now-common practice of claiming drug formulations based on the results of administering those formulations rather than based on structure, e.g. their ingredients or method of manufacture.   To be sure, this claiming technique offers multiple advantages.  First, it affords broader patent protection because it theoretically covers all bioequivalent formulations regardless of their composition.  Second, it defines the product in a way that is less likely to be discussed in the prior art.  But such claims also seem to lack a nexus to the invention at issue:  a formulation.  And there is case law holding that claim language directed to results, rather than structure, is not limiting.  See, e.g., Minton v. Nat’l Assoc. of Secs. Dealers, Inc., 336 F.3d 1373, 1381 (Fed. Cir. 2003); Texas Instruments v. ITC, 988 F.2d 1165, 1172 (Fed. Cir. 1993).  Thus, Judge Lourie may have identified a new means for attacking results-oriented product claims that lack structural limitations.