Pfizer says it reached a settlement with Teva Pharmaceuticals that allows the generic drugmaker to launch a copycat version of its popular erectile dysfunction drug Viagra in 2017.

Pfizer says Teva will pay an undisclosed royalty for a license to produce a of Viagra, one of New York-based Pfizer's best-selling drugs. Viagra generated about $1.14 billion in U.S. sales last year.

Pfizer's patent protecting Viagra from generic competition expires in April 2020, but Teva will be allowed to launch its generic version Dec. 11, 2017.

Pfizer Inc. had sued Teva in 2010 over the Israeli drugmaker's plans to introduce a generic version of Viagra.

The patent protecting another , Eli Lilly and Co.'s Cialis, also expires in 2017.