Shares of Teva Pharmaceutical (TEVA) - Get Report were up more than 2% Monday afternoon after the company announced it was launching a generic version of Pfizer's (PFE) - Get Report popular Viagra pill.

The erectile dysfunction pill is one of the most popular drugs on the market, but it doesn't have wide competition due to a patent that does not expire until 2020. However, Teva negotiated a deal to launch its own generic version in 2013.

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Pfizer is also being proactive about the coming patent expiration, announcing plans to launch its own generic version of the $65-a-pill remedy.

"The launch of Teva's sildenafil tablets brings an affordable generic treatment option to the estimated 18 million men in the U.S. who are diagnosed with erectile dysfunction," said Brendan O'Grady, Executive Vice President, North America Commercial at Teva. "Our team has made it a priority to ensure that patients are able to access this medicine-through both traditional and more innovative channels."

Analysts have suggested that increased competition from generic competitors to bring the price of Viagra down as much as 90%, according to Fox Business. 

Viagra has annual sales of about $1.4 billion.

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