"We are lowering original Viagra's price to be in line with generic versions because we are committed to ensuring that Viagra patients continue to have access to the original - made by Pfizer, and at a competitive price," Scott Wilks from Pfizer's Canadian subsidiary said in a statement.
The patent on Viagra had been due to expire in 2014 in Canada. The Supreme Court threw the door open to generics immediately on November 8 when it ruled that Pfizer had not provided enough details when it filed its patent.
That challenge had been mounted by Israeli-based Teva Pharmaceutical Industries Ltd, the world's largest drug maker, which said it expected to offer a generic version at a substantially lower price.
Pfizer said cheaper generic entries had already arrived in Canadian stores. It did not identify the suppliers, but said it had now cut its typical pack of four 100 mg pills to about C$37 ($37) from C$49, effective immediately.
The Viagra patent in the United States is still valid. Viagra is not available over the counter, so Americans cannot simply to go into a Canadian pharmacy to buy the drug.
(Reporting by Randall Palmer; Editing by Janet Guttsman and Andrew Hay)