Canadian court voids patent for Viagra

The Supreme Court of Canada voided Pfizer Canada's patent for the impotence drug Viagra on 8 November because of what it says is a misleading patent application submitted in 1998.

Pfizer’s Canadian patent for the erectile dysfunction drug was divided into seven parts and covered 260 quintillion different chemical compounds. According to the court’s ruling, Pfizer had, however, failed to disclose that a compound called sildenafil was the main active compound. The company claimed there were seven other active ingredients.