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Pharmaceuticals and healthcare

Patent law: Infringement of patent claims with numerical ranges

Patent claims with numbers or measurements are widespread, and commonplace in many different industries, including medical devices or drug formulations. For competitors the question arises as to the relevance of such features. Can they rely on these features, according to which there is no patent infringement if the product has properties that are outside the claimed range? The Swiss Federal Patent Court recently had to deal with this question. Enjoy reading our contribution.

22.02.2022 Matthias Stauffacher  •   Dr. Christoph Willi, LL.M.

An example by way of introduction: According to the wording of a patent claim, patent protection is sought for a tablet containing a certain amount of an active pharmaceutical ingredient, for example for 45-60 percent by weight. Does a tablet with a higher amount of the active ingredient infringe the patent, for example if the tablet contains 64.3% by weight of that active ingredient?


In the deferasirox case, the Swiss Federal Patent Court had to deal with exactly this question. For the first time, it examined a patent infringement by equivalent means for number or measurement indications.

The dispute concerned a Novartis drug for the treatment of iron overload resulting from frequent blood transfusions in patients with anemia. Novartis initially marketed deferasirox as a dispersible tablet and replaced it with a swallowable tablet in October 2019. The swallowable tablet no longer needed to be dissolved in water or an aqueous solution before ingestion.

The Federal Patent Court examined both the validity and infringement of European Patent EP 2 964 202, which Novartis invoked. The patent claims relate to a swallowable film-coated tablet containing deferasirox or a pharmaceutically acceptable salt thereof up to 45 to 60%, based on the tablet’s total weight, as well as other excipients not of interest here.

The disputed tablet contained 64.3% deferasirox. The proportion of the active ingredient, therefore, exceeded the claimed range of 45 to 60% by weight. All other characteristics were indisputably fulfilled. The case raised the question for the court as to what significance a numerical range in a patent claim should have, particularly if a product is said to infringe the patent claim despite a feature that deviates from it.

What is the significance of numeric ranges in a patent claim?

Like verbally described features, numbers and measurements also participate in the binding force of a patent claim. They are decisive in determining the scope of protection of a patent - but also in limiting it. Since linguistically formulated general terms always contain a certain abstraction, numbers and measurements have a higher degree of clarity. Therefore, competitors may generally assume that everything for which protection is sought is set forth in the patent claim. Exceeding or falling short of these features is generally not patent-infringing.

And yet the Federal Patent Court holds a patent infringement. How could this happen?

No literal patent infringement

First, the Federal Patent Court clarified that there could not be a literal patent infringement: "If a measured value is outside a numerical range, the value is no longer covered by the wording of the patent claim." This is even more true if the claim does not contain any wording from which it can be directly and unambiguously inferred that the claimed numerical range is not strictly limited, for example, by using a term such as "essentially" or "approximately" in the range of. The court therefore concluded that the language in the patent claim is not merely exemplary in nature.

The Federal Patent Court holds, however, that there is a patent infringement under the doctrine of equivalence. In Switzerland, for establishing a patent infringement by equivalent means one must assess how the replaced feature differs from the claimed feature. In the case of deferasirox, therefore, the court had to assess the relevance of the difference in the proportion by weight of the active ingredient in the total weight of the tablet (64.3% instead of the range between 45 to 60% by weight of deferasirox).

Application of the Swiss three-step test

As a first step, following the scheme set out by the Federal Supreme Court, the Federal Patent Court examined the equal effect of the modified feature. In doing so, it examined whether the modified feature fulfills the same function as the claimed feature. The Federal Patent Court affirmed the equal effect because the tablet with 64.3% by weight of deferasirox was bioequivalent to Novartis' tablet. The bioequivalence is confirmed by the fact that the generic tablet was approved in an abbreviated drug application procedure to which bioequivalence is a prerequisite.

On the second question, the Federal Patent Court examined whether the same effect of the replaced feature was recognizable. In doing so, the court evaluated whether the equal effect of the modified feature was accessible to the skilled person. The Federal Patent Court concluded that the patent specification did not require strict compliance with the upper limit of the claimed range. Rather, it was clear from the patent specification that the intention was to increase the proportion of active ingredient. An increase in the proportion of active ingredient of less than 10% would not be considered as the formulation being no longer safe or effective. Even a higher proportion of active ingredient in deferasirox was conceivable, even taking into account the additional excipients mentioned in the patent.

In a third step, the Federal Patent Court assessed whether the skilled person reading the patent specification would conclude that the patentee had deliberately formulated the claim so narrowly thereby waiving protection for an embodiment with equal effect that would have been accessible to the skilled person. In assessing this question, the court emphasized in principle, that sufficient consideration must be given to legal certainty. Nevertheless, a value outside of the claimed numerical range would fall under the scope of the patent if it was within generally recognized tolerances. In this case, the strict observance of the range would not be of technical significance. In light of the total weight of the tablet the accepted tolerance below 7.5% by weight. Therefore, the court concluded that the disputed tablet was within the accepted tolerances for pharmaceutical formulations, and infringed Novartis' patent by equivalent means.

Implications of the decision

As far as can be seen, this is the first decision in Europe about formulations of deferasirox. In the EU member states, and due to a pediatric extension, deferasirox is patent-protected as an active ingredient until February 28, 2022. The court struggled with its decision, but felt bound by the restrictive case law of the Federal Supreme Court, but indicated that it would be willing to review the matter in a main proceeding with 5 judges on its panel. In this preliminary injunction proceeding, however, the legal certainty seems to have fallen short, due in part to the case law of the Federal Supreme Court, which is significantly more strict than in other European countries when assessing infringement by equivalent means.

This is regrettable for Switzerland as a production place, and  negative consequences might arise, including for manufacturers of medical devices operating in Switzerland.  Manufacturers may no longer rely on their belief  that numerical ranges in a patent claim are conclusive and binding. They too must always be prepared for their product being held as patent infringing, even if its features lie outside the claimed range.

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