Pfizer Inc. v. Novopharm Ltd.

"Viagra patent invalidated for insufficient disclosure—Pfizer must fully disclose the true invention."

Short Summary :

Pfizer’s Canadian patent on Viagra (sildenafil), which broadly claimed a class of compounds including sildenafil, was struck down by the Supreme Court of Canada due to failure to disclose that sildenafil was the only effective compound.

Facts :

Pfizer obtained Canadian Patent No. 2,163,446 claiming a broad class of compounds (with narrowing tiers), eventually naming nine “especially preferred” compounds—including sildenafil—and two individual compounds (claims 6 and 7), of which claim 7 named sildenafil.

Novopharm (now Teva) challenged the patent’s validity under Canada’s PMNOC regime, alleging invalidity on grounds of obviousness, lack of utility, and insufficient disclosure

Findings :

Federal Court (Kelen J., 2009): Recognized concerns about nondisclosure but held claim 7 (sildenafil) was sufficiently disclosed as separately claimed.

Federal Court of Appeal (2010): Agreed; viewed each claim as a separate invention and upheld disclosure sufficiency for claim 7.

Supreme Court of Canada (2012, unanimous opinion by LeBel J.) :

Held that one must assess the specification as a whole, not claim-by-claim. The single inventive concept was the use of sildenafil for treating erectile dysfunction.

Pfizer’s failure to disclose that only sildenafil (and not the broader class) had been tested meant a skilled person couldn’t practice the invention without additional experimentation, violating section 27(3) of the Patent Act.

The patent was deemed invalid due to insufficient disclosure; the Supreme Court dismissed Pfizer’s PMNOC prohibition application

Suggestion / Implications :

Patent applicants must fully disclose the true inventive concept, especially in pharmaceuticals.

Cascading (genus-to-species) claims can mislead if the effective compound isn’t clearly identified.

Courts will not allow patentees to “game the system” by withholding key information while enjoying a monopoly.

Judgment with Date :

Supreme Court of Canada decision: November 8, 2012 (2012 SCC 60) — appeal allowed, patent held invalid for insufficient disclosure