A federal judge in Virginia has ruled in favor of Pfizer in the pharmaceutical giant’s Viagra patent infringement case against generics maker Teva Pharmaceutical Industries. The decision secures Pfizer’s U.S. patent exclusivity on the blockbuster erectile dysfunction treatment for eight more years.
Pfizer’s original patent on sildenafil citrate, Viagra’s active ingredient, is due to expire next year. Teva argued that a second patent, on the use of sildenafil citrate specifically to treat erectile dysfunction, is unenforceable. The court upheld the second Pfizer patent, however, which doesn’t expire until 2019.
The decision, by Judge Rebecca Beach Smith, provides a modicum of relief for Pfizer, which faces imminent loss of patent protection for its cholesterol-lowering medicine Lipitor, the top-selling drug in the world. Viagra sales reached $1.9 billion in 2010, about half of which are U.S. sales, compared with total sales of $10.7 billion for Lipitor.
“We are pleased that the court recognized the validity and enforceability of our Viagra patent for the treatment of erectile dysfunction,” says Amy W. Schulman, Pfizer’s general counsel.
Viagra is the first commercialized therapy in a category of drugs that now includes Eli Lilly & Co.’s Cialis and Bayer’s Levitra. It was discovered serendipitously during clinical trials of sildenafil citrate as a chest pain treatment. The drug performed poorly for that indication, but men participating in the trial reported experiencing spontaneous erections.
The court’s decision, which remains subject to appeal, prevents Teva from receiving approval for a generic form of Viagra until October 2019. Pfizer acknowledges other patent challenges to Viagra, although no trials in those cases have been scheduled.
The decision surprised some observers, says Damien Conover, a stock analyst with Morningstar. “I think most people expected the patent exclusivity for Viagra to run out next year in most major markets,” he says.
“Pfizer is not completely out of the woods yet,” Conover adds, pointing to other pending challenges to the Viagra patent. “But Teva is a nice barometer for what will likely happen in those cases.”