5 blockbuster name brand drugs facing patent expiration

With patent expirations looming and already passing for some of the nation's bestselling name brand drugs, Big Pharma is facing major revenue challenges in 2012

"Patents on a number of the largest-selling drugs will expire in late 2011 and 2012, which is increasing pressure on most branded drug companies at a time when the quality of the late-stage pipelines remains relatively weak," said Marie Fisher-Sabatie, vice president and senior analyst of Moody's Corporate Finance Group. 

[See also: Patent expirations will cost pharma billions]

Here are five blockbuster name brand drugs facing patent expiration. 

1. Seroquel. Seroquel, manufactured by AstraZeneca, lost its marketing exclusivity on March 26, 2012. In an article by CBS News, an analyst investor said the loss of the drug's patent could mean a loss of $4.3 billion for the company - nearly half of its total pretax profit. Despite disagreeable side effects, like weight gain and diabetes, the drug pulled in approximately $5.3 billion in revenue in 2010, and as a whole, AstraZeneca walked away with $33.3 billion. Experts agree the patent expiry shouldn't affect AstraZeneca too much; Seroquel is about 13 percent of the company's revenues. Still, the drug is "enormously profitable," said Berstein Research's Tim Anderson, in a meeting following the company's Q4 earnings call. "AZN faces many big patent expiries between 2010 and 2015, such as Seroquel (U.S. expiry early 2012), product with pretax margins greater than 80 percent," he said. 

2. Lexapro. Lexapro, which is used to treat anxiety and depression, had a patent that expired on March 14, 2012. And, according to an article by the Rottenstein Law Group, the patent's expiration means the controversial drug is looking to become more widespread than ever. "That will leave the door open for other drug companies to sell Lexapro in generic form," the article read. It added the anticipated loss in revenue from Lexapro, which accounted for approximately 59 percent, or $2.8 billion, of Forest Laboratories' 2010 sales, has the company keeping investors apprised of new products it acquired to make up for the impending shortfall. "Forest has made a bundle on Lexapro - the company's $11 billion revenue is projected to drop by as much as one-fourth after the drug's patent expires," the article read. Lexapro also ranked 19th in sales in 2010, due largely to a growing demand for anti-depressants.