The Supreme Court of Canada, in its first patent decision in 8 years, has declared Pfizer’s Canadian patent for Viagra to be invalid. This has now cleared the way for Teva Canada Ltd., which challenged the patent, to bring a generic version of Viagra onto the market. In order to obtain approval from Health Canada to sell a generic version of a patented drug, a generic manufacturer must prove that the patent covering the drug is not infringed or is invalid. Pfizer’s patent was due to expire in 2014.
Sildenafil, the compound used in Viagra, was originally a cardiovascular drug. It was later discovered that sildenafil is also useful in treating erectile disfunction (“ED”) and Pfizer obtained a Canadian patent for this use. This is an example of a patent for a new use for an old compound. More…