Patenting Pharmaceutical Drug Formulations: Withstanding Litigation and PTAB Challenges

The development of pharmaceutical products for FDA approval in the U.S. is often expensive and unpredictable. Not surprisingly, such products are often protected by more than one patent. There is a recent trend for ANDA filers not to challenge a drug substance patent, which regularly issues from a medicinal chemistry patent application. Instead, the ANDA filers are going after the drug product patents, which can be all about formulations, particularly if the U.S. formulation product patent's expiration date is after that of the drug substance patent.

Formulations, however, may evolve and provide different means of administration and/or dosing compared to the medicinal chemistry patent. As it is developed over time, the formulation may be separately patentable over earlier U.S. patent filings and might offer many years of additional patent exclusivity.

Pharmaceutical formulation technology can be highly sophisticated and possess unpredictability and novelty relative to the drug substance patent. Challenges arise as the USPTO may insist that formulation claims in these subsequent applications be very narrow.

Paragraph IV ANDA filers may take the position that their generic formulation does not infringe such narrow claims. On the other hand, ANDA filers may also try to invalidate formulation claims. Federal Circuit opinions such as Endo Pharmaceuticals Solutions Inc. v. Custopharm Inc. (Fed. Cir. 2018) demonstrate how unpredictability in the art can support the patentability of drug formulation claims. However, Persion Pharms. L.L.C. v. Alvogen Malta Operations LTD. (Fed. Cir. 2019), shows inherency arguments may be a stumbling block for patent owners.

A challenge may remain in obtaining pharmaceutical formulation claims that are broader than mere picture claims. Patent drafters may benefit from using the Section 112(f) (means-plus-function) format for formulation claims. The panel will analyze Judge Salas' construction of a pharmaceutical means-plus-function claim in Nautilus Neurosciences Inc. v. Wockhardt, United States L.L.C. (D. N.J. 2013).

To be sure, a means-plus-function claim may be construed narrowly. Still, the kicker is that in addition to the structure, materials, and acts in the specification, the patent owner gets equivalents thereof. That has been construed as literal equivalents to the means. What "literal equivalents" means exactly is unclear as there is scarce judicial guidance for pharmaceutical formulations in this area of case law.

However, as shown in Ex parte Gleave, Appeal No. 2012-004973 (2014), drafting a formulation claim as "a composition comprising a means for [effect] and a pharmaceutically acceptable carrier" may be a successful prosecution strategy.

Biosimilars present a developing area of case law for formulation claims. The panel will discuss formulation claims in a biosimilar context.

Listen as our authoritative panel of U.S. patent attorneys teaches how to successfully prosecute and withstand litigation and PTAB challenges of formulation claims.