By the time Prozac's patent expired in 2001, it was responsible for more than one-third of Lilly's revenue. The company laid off employees but went on to introduce replacements, notably Cymbalta.
But Lilly and other pharmaceutical giants face a market in which generic antidepressents are a growing force, The Indianapolis Star reported Sunday. While antidepressant use is still on an upswing, 82 percent of all prescriptions last year were for generic drugs, the pharmaceutical data company IMS Health said.
Cymbalta, introduced in 2004, is second only to the anti-psychotic Zyprexa as a moneymaker for the company. Cymbalta's sales grew 28 percent last year, spurred by commercials aimed at consumers.
Barbara Ryan, an industry analyst for Deutsche Banke, says Cymbalta sales will grow more slowly in coming years. She said drugs have a life cycle during which sales slow as they mature.
The company's official position is optimistic.
"Yes, there are more generics out there, and that does create pricing pressures within any category," a spokesman, David Shaffer, said. "But that's just a normal part of the life cycle and a normal part of our business to deal with it."