Canada’s Intellectual Property Firm

Obviousness of Lilly’s tadalafil (CIALIS) dosage form patent stands

Authored byLynn Ing

The Federal Court of Appeal has dismissed Lilly’s appeals of judgments that held Canadian Patent No. 2,371,684 (the 684 patent) claims invalid. The decision, Eli Lilly v Apotex, 2023 FCA 125, was issued on June 2, 2023.

The 684 patent relates to the use of oral pharmaceutical unit dosage forms containing tadalafil (2-20 mg, 2.5 mg, 5 mg, 10 mg, 20 mg, 5-20 mg) for the treatment of erectile dysfunction (ED). Lilly markets tadalafil as CIALIS. Lilly brought four infringement actions – against Apotex, Pharmascience/Riva, Mylan, and Teva; the defendants counterclaimed for a declaration of invalidity. In a single set of reasons, the Trial Judge found Lilly would have been entitled to relief due to infringement by each defendant if the asserted claims were valid, but held the claims were invalid for anticipation and obviousness (see our Rx IP Update report).

On the appeal, there was no issue as to the Trial Judge’s construction of the claims or factual findings.

Lilly argued that the Trial Judge erred in law in her approach to construing the inventive concept in the obviousness analysis.  Applying the Trial Judge’s factual findings, however, the FCA concluded that even if the new inventive concept proposed by Lilly was accepted, the finding on obviousness must stand. The prior findings – including that dose range studies would be routine steps – applied to the proposed inventive concept that “the claimed dosages of tadalafil, orally administered, provide efficacy to treat male ED, including the minimization or elimination of flushing as compared to larger doses of tadalafil”. 

While agreeing with the Trial Judge’s findings that drug dosing of tadalafil for the treatment of ED was routine work having regard to the prior art, the FCA declined to endorse this statement at large: “There may be cases where dosage selection is not routine.”

It was unnecessary for the FCA to address the arguments on the issues of anticipation and whether the 648 patent is a selection patent.

Should you have any questions, please do not hesitate to contact a member of the Pharmaceutical Litigation Group.

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