Almost seventy years ago, Congress passed the 1952 Patent Act, which included 35 U.S.C. §112(6), the first statutory language describing means-plus-function ("MPF") claims. MPF claims define an element, in a combination claim, by its function instead of its structure. This statutory provision remains in action since then, though rebranded as §112(f) in the Leahy-Smith America Invents Act, 125 Stat. 284 ("AIA"). Despite the rebranding, the statutory language still reads:

35 U.S.C. §112(f) ELEMENT IN CLAIM FOR A COMBINATION.—An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof..

MPF claims, often thought of as very narrow, can in fact provide greater protection for patent applicants than can other types of claims, including for claims drawn to pharmaceutical subject matter. That is because the statutory term "equivalents" does not reference the doctrine of equivalents, but rather refers to literal equivalents of structure, material, or acts that perform the same function. By encompassing literal equivalents, an inventor's claims can better protect an inventor's rights. It can also better prevent competitors from drafting around the literal scope compared to claims that recite particular elements, as MPF claims will encompass alternatives that provide the same function as claimed.

In some circumstances, MPF claims describe the invention in a clearer, more precise, and even broader way than purely structural claims. Specifically, the functional part in the §112(f) combination covers the "corresponding structure, material, or acts described in the specification and equivalents thereof." MPF claims are underutilized in pharmaceutical patents, but there are some that have sallied forth and have issued.

Examples of Issued MPF Claims

In Ex parte Gleave, Appeal 2012-004973 (P.T.A.B. Jan. 22, 2014), the PTAB reversed an examiner's rejection and allowed a pharmaceutical claim using MPF language.1 Applicants amended claim 33 to read:

33. (currently amended) A pharmaceutical composition comprising a

(a) means for reducing the amount of active hsp27 in cancerous cells [by sequence specific interaction with Seq. ID No. 91] and

(b) a pharmaceutically acceptable carrier.

This claim was rejected on several grounds, including §112(f). With respect to the MPF language, the examiner explained:

the instant specification does not describe any means for reducing the amount of active hsp 27 via sequence specific interaction other than by antisense oligonucleotide or RNAi inhibition. Therefore, the claims are broader than the instant disclosure, as this is not a defined genus that has been described by the specification. The specification does not have a sufficient disclosure of the structure that corresponds to the claimed function. Means plus-function claims require disclosure in the specification even if the means are already well known in the art.

On appeal, the PTAB agreed with Applicants that the MPF limitation was proper:

We agree with Appellants that the structures disclosed in the Specification as having the function recited in the claims are limited to (a) the specific antisense oligonucleotides in Example 1, (b) the specific RNAi molecules of Example 5, and (c) equivalents thereof, that are effective in reducing the amount of hsp27 in cancerous cells.

Appeal 2012-004973 at *7. As will readily be comprehended, such a claim could be particularly effective against a 505(b)(2) challenger2 or a competitive innovator.

Another instance of pharmaceutical MPF claims surviving scrutiny can be found in U.S. Patent No. 10,413,611 ("the '611 Patent"), which claimed, in a combination:  "(b) means for keeping the pharmaceutical composition in liquid phase up to a temperature of about 40° C in vitro."

During prosecution, the examiner rejected this claim, explaining that it

fails to recite a combination of elements as required by that statutory provision and thus cannot rely on the specification to provide the structure, material or acts to support the claimed function. As such, the claim recites a function that has no limits and covers every conceivable means for achieving the stated function, while the specification discloses at most only those means known to the inventor. Accordingly, the disclosure is not commensurate with the scope of the claim.

The examiner was persuaded by Applicant's response that "claim 1 recites a poloxamer and a means for, meaning it is not a single means claim because it does recite a combination of elements (a poloxamer in combination with means for)." The examiner allowed the claim which issued as independent claim 1 in the '611 patent. Such a claim could be very useful against an ANDA challenger3 who copies the active ingredient but tries to pirate the invention by changing the formulation.

Further examples of issued pharmaceutical MPF claims include:

  • U.S. Patent No. 9,149,464 Bendamustine Derivatives and Methods of Using Same
    • Independent Claim: 13. A pharmaceutical composition, comprising (a) [compound], and (b)a means for increasing the circulation time of the compound in an aqueous environment. (emphasis added)
  • U.S. Patent No. 7,579,380 Modified Release Formulations of a Buproprion Salt
    • Independent Claim: 20. A pharmaceutical composition, comprising at least one core which is surrounded by at least one osmotic subcoat, at least one control-releasing coat which surrounds the at least one osmotic subcoat, wherein the at least one core comprises bupropion hydrobromide and at least one excipient, wherein the at least one osmotic subcoat comprises at least one osmotic agent and at least one osmotic deposition vehicle, and a means for releasing the bupropion hydrobromide from the composition. (emphasis added)
  • S. Patent No. 7,670,617 Sequential Drug Delivery Systems
    • Independent Claim 1. A pharmaceutical composition comprising an active ingredient in a dosage form comprising a first portion, a second portion and means for sequential release of said first portion and said second portion at a desired site within a subject;... and wherein said means for sequential release comprise means for sequentially controlling the activity of said pH-adjusting substances so that said first pH-adjusting substance attains peak activity in the localized environment of the active ingredient before said second pH-adjusting substance attains peak activity in the localized environment, whereby the localized environment of the active ingredient attains a first pH and then a second pH; wherein said means for sequentially controlling the activity of said pH-adjusting substances comprises at least one coating that surrounds said second pH-adjusting substance; said first pH-adjusting substance being peripheral to said coating; and wherein said active ingredient is peripheral to said coating in said dosage form. (emphasis added)
  • S. Patent No. 9,446,076 Pharmaceutical Composition for the Treatment of Heart Diseases
    • Dependent Claim 9. The pharmaceutical composition of claim 1, wherein said at least one pharmaceutically acceptable excipient comprises at least one component selected from the group consisting of growth factors, cytokines, proteins involved in organogenesis signaling, pharmaceuticals, platelet lysate, serum, isotopes, means for tracing cells in vivo, diluents, lubricants, matrix or scaffold materials, and combinations thereof. (emphasis added)
  • S. Patent No. 10,335,405 Non-Burst Releasing Pharmaceutical Composition
    • Independent Claim 11. An abuse deterrent oral pharmaceutical composition comprising a tamper resistant controlled release matrix, wherein the tamper resistant controlled release matrix comprises a means for preventing the crushing, grating, grinding, cutting, solvating, or dissolving of the tamper resistant controlled release matrix comprising:... (emphasis added)

Takeaway: Overall, MPF language can be a powerful tool in drafting pharmaceutical claims to encompass broader claim scope and thus more fully protect an inventor's rights and provide greater protection against infringement. While there have been relatively few pharmaceutical patents utilizing this language, some MPF pharmaceutical claims, as seen herein, are being issued by the USPTO.

1 For a more detailed analysis of this decision, see Irving and Lewis, An Issued Life Science MPF U.S. Patent Claim: Ex parte Gleave, Finnegan Prosecution First Blog,

2 Federal Food, Drug, and Cosmetic Act, 21 U.S.C. 355(b)(2): An application submitted under paragraph (1) for a drug for which the investigations described in clause (A) of such paragraph and relied upon by the applicant for approval of the application were not conducted by or for the applicant and for which the applicant has not obtained a right of reference or use from the person by or for whom the investigations were conducted ...

3 Federal Food, Drug, and Cosmetic Act, 21 U.S.C. § 355(j) Abbreviated new drug applications

  1. Any person may file with the Secretary an abbreviated application for the approval of a new drug.
  2. (A) An abbreviated application for a new drug shall contain—
    (i) information to show that the conditions of use prescribed, recommended, or suggested in the labeling proposed for the new drug have been previously approved for a drug listed under paragraph (7) (hereinafter in this subsection referred to as a "listed drug");...
    (iii) information to show that the route of administration, the dosage form, and the strength of the new drug are the same as those of the listed drug referred to in clause (i) ...;
    (iv) information to show that the new drug is bioequivalent to the listed drug referred to in clause (i), ...;
    (v) information to show that the labeling proposed for the new drug is the same as the labeling approved for the listed drug referred to in clause (i) ...;
    (vii) a certification, in the opinion of the applicant and to the best of his knowledge, with respect to each patent which claims the listed drug referred to in clause (i) or which claims a use for such listed drug for which the applicant is seeking approval under this subsection and for which information is required to be filed under subsection (b) or (c)—

(I) that such patent information has not been filed,
(II) that such patent has expired,
(III) of the date on which such patent will expire, or
(IV) that such patent is invalid or will not be infringed by the manufacture, use, or sale of the new drug for which the application is submitted; and...

Originally published August 17, 2020.

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