Canadian Court Cancels Viagra Patent

A Canadian court recently invalided Pfizer’s Viagra (sildanafil) patent for failing to adequately disclose which compounds were useful for the treatment of erectile dysfunction (ED). Because a skilled reader, having only the specification, would not be able to put the invention into operation, the patent was invalid.  Here’s what the court had to say about it:

The patent system is based on a “bargain”: the inventor is granted exclusive rights in a new and useful invention for a limited period in exchange for disclosure of the invention so that society can benefit from this knowledge.  Sufficiency of disclosure lies at the very heart of the patent system, so adequate disclosure in the specification is a precondition for the granting of a patent….

…By withholding from the public the identity of the only compound tested and found to work, sildenafil, the patent did not fully describe the invention. Obviously Pfizer made a conscious choice not to disclose the identity of the only compound found to work, and left the skilled reader guessing. This is contrary to the statutory requirement to fully disclose the invention.

This case serves as an important reminder to all inventors.  An invention must be fully disclosed in a patent application.  While there is sometimes a delicate dance between trade secrets and disclosure, one simply cannot have a patent on a secret invention.  Close collaboration between patent counsel, inventors and technical experts can help to ensure disclosure requirements are met when drafting a patent application.

The Greenbaum Patent Blog is the blog of Eric A. Greenbaum esq, founder of Greenbaum P.C., an intellectual property law firm located in Long Island New York.  The firm focuses on patent and trademark prosecution, licensing and contract work for independent inventors, small companies and start-ups in New York City (NYC,) Long Island and around the country.  Intellectual property law is a rapidly evolving field of law and the issues are very fact-specific.  Nothing on this blog should be taken as legal advice.  Consult with an attorney for help on your particular case.

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