An appeals board of the U.S. Patent and Trademark Office (USPTO) has partially rejected a patent on Pfizer Inc’s impotence drug Viagra because it works in a way similar to the Chinese herb Yin Yang Huo, otherwise known as Horny Goat Weed. See http://en.wikipedia.org/wiki/Epimedium for details of this plant.
This February 12 decision upheld an earlier finding that an element of the Viagra patent did not represent a new invention.
Interestingly the claims were cancelled following the patentee, Pfizer, filing a patent infringement lawsuit against rival pharmaceutical company Eli Lilly and Co, which makes the competing drug Cialis.
The board of patent appeals ruled that a chemical ingredient of Yin Yang Huo, which is used to treat impotence and sometimes sold as an alleged aphrodisiac, is similar to the enzyme inhibitor found in Viagra.
The Pfizer patent which is not due to expire until 2019, enables Pfizer to maintain a monopoly on sildenafil (Viagra) which is apparently used to treat erectile dysfunction. Last years sales of the drug in the US exceeded $2 billion.
There are apparently a lot of horny old goats out there…
