| NEW YORK
NEW YORK Drugmaker Wyeth won U.S. approval to sell a drug called Pristiq to treat depression, the U.S. Food and Drug Administration said on Friday.
An FDA spokesperson confirmed the approval, but provided no other details.
Pristiq is a derivative of Wyeth's widely used Effexor depression drug and the company had hoped it would be approved long before Effexor loses its U.S. patent protection in 2010 and faces generic competition.
But some analysts have dismissed Pristiq as a "me, too" drug, with few distinguishing characteristics and modest sales potential.
Wyeth also has tested Pristiq as a treatment for hot flashes in post-menopausal women, but the FDA last summer said it could not approve the drug for that condition until Wyeth resolved concerns about potentially serious heart and liver problems. The company plans to begin a new study in coming months to verify its safety.
The drugmaker has not cited any major advantages Pristiq might have over the $3.8 billion-a-year Effexor in treating depression, but has suggested it may be less likely to interact with other medicines because it is broken down differently.
"This is a very important condition," said Wyeth Chief Executive Officer Bernard Poussot, "and physicians need all the options" in treating patients.
Despite skepticism among many industry analysts about the drug's commercial appeal, Poussot said in an interview that Wyeth remains confident Pristiq will eventually garner annual sales of $1 billion or more as a treatment for depression.
Mehta Partners analyst Shaojing Tong said Pristiq may surprise naysayers and post decent sales despite its lackluster profile, even after cheaper generic forms of Effexor hit the market.
"It could wind up with sales of $500 million to $1 billion because so many patients switch between depression drugs" to obtain relief, and Pristiq will be one of the relatively few available options, Tong said.
Wyeth in December said a low-dose 50-milligram form of Pristiq was effective in two late-stage depression trials and far better tolerated than a 100-milligram version that failed to win U.S. approval in early 2007.
The 100-milligram version had proved ineffective in one of the Phase III studies, tarnishing overall results of the two trials.
Wyeth submitted results last summer of the studies, one conducted in the United States and one conducted overseas, to the U.S. Food and Drug Administration.
In studies of the 100-milligram dose of Pristiq conducted more than a year ago, a high percentage of patients complained of nausea and stopped taking the drug, creating doubts that doctors would prescribe it or patients take it even if it were approved.
Wyeth scrapped that formulation and began studies of the now-approved 50-milligram pill, hoping it would not cause nausea. The percentage of patients who dropped out of the trials because of side effects was similar to those who received a placebo, indicating the lower dosage pill was tolerated.
The FDA in early 2007 refused to approve the 100-milligram formulation, in part because of long-standing quality-control lapses at a Wyeth plant in Puerto Rico where Pristiq was to be manufactured. The problems have since been fixed and the 50 milligram pill is manufactured there.
Shares of Wyeth were unchanged in after-hours electronic trading on Friday from their closing share price of $43.62 on the New York Stock Exchange.
(Additional reporting by Lisa Richwine; editing by Carol Bishopric)