Drug-related patent held invalid for double patenting and anticipation, but not obviousness

June 3, 2010

Merck v. Pharmascience, 2010 FC 510 (Federal Court).

In a decision rendered May 11, 2010 under the Patented Medicines (Notice of Compliance) Regulations, Justice Hughes of the Federal Court of Canada found Canadian Patent No. 2,173,457 (the ’457 Patent) to be invalid, and accordingly dismissed an application by Merck which sought to prohibit the Minister of Health from issuing a notice of compliance to Pharmascience, allowing Pharmascience to market its generic version of the medicine finasteride for treating male pattern baldness.

Claim 5, a “Swiss-type” claim, was the only claim at issue and was construed by the court as claiming “the use of finasteride for the preparation of a medicament adapted for oral administration useful for the treatment of male pattern baldness in a person and wherein the daily dosage is about 1.0mg.”Although this claim in the corresponding European patent had been upheld by the UK Court of Appeal, counsel for Pharmascience, Stikeman Elliott LLP, was successful in invalidating claim 5 on two grounds: double patenting and anticipation.

Under a double patenting analysis, the court is simply required to compare the claims of an earlier patent owned by the same patentee with the claims of the patent at issue to determine whether they are “identical or co-terminus” or “obvious” (and thus invalid in either case).This is to prevent so-called patent “evergreening”. In this respect, Merck already held a first patent – Canadian Patent No. 1,302,277 (the ’277 patent) – directed to a range of compounds, including finasteride, that were stated to be useful for the treatment of androgenic alopecia, including male pattern baldness. Claim 15 of the ‘277 Patent, for instance, claimed “the use of finasteride for treating male pattern baldness” while claim 19 claimed “the use of finasteride for the manufacture of a medicament for the treatment of androgenic alopecia”. Of importance, these claims were not limited to any particular dosage or dosage range, even though the disclosure stated that “the daily dosage of the products may be varied over a wide range varying from 5 to 2,000 mg, preferably from 5 to 200 mg.” As a result, the only difference between claim 5 of the ‘457 Patent and claims 15 and 19 of the ‘277 Patent was that claim 5 specified a dosage of 1 mg/day. With the earlier claims not being limited by dosage, Justice Hughes found that the claims of the two patents were both “identical or co-terminous” and “not patentably distinct”, meaning claim 5 of the ‘457 Patent was invalid.

As for the test of anticipation or lack of novelty, the law requires that the prior art must both disclose and enable that which is claimed in the patent under consideration. In this case, the court found it was clear that if one were to make a medicament in accordance with claim 5 of the ’457 Patent, a number of claims of the ’277 Patent would be infringed.In addition, it would have been within the expected skill of a person skilled in the art, as the ’457 Patent itself acknowledged, to determine an appropriate dosage for a given person. There was therefore no “undue burden” in determining an appropriate dosage,and the ’277 Patent therefore clearly both disclosed and enabled that which was claimed in claim 5 of the ’457 Patent.

Of note, this was one of those rare situations where a patent was held invalid for lack of novelty but not obviousness. In light of two research papers published after the relevant prior art, but before the filing of the application for the ‘457 Patent, Justice Hughes found that a researcher would have been sufficiently discouraged from pursuing research with finasteride for treating male pattern baldness that the subject matter of claim 5 became inventive for the relevant period of time.

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