Pfizer's Pristiq antidepressant comes up short for kids

When the FDA approved Wyeth's antidepressant Pristiq in 2008, the nod came with a number of provisions to do postmarketing studies, including one in pediatric patients. Seven years later, Pfizer ($PFE), which bought Wyeth in a 2009 megamerger, has fulfilled that obligation to disappointing results. The drug failed to hit its endpoint.

The company reported on Thursday that in a Phase III study of major depressive disorder in children 7 to 17 Pristiq ER was no more effective than a placebo. Pfizer said it was the first of four Phase III pediatric trials being conducted under its commitment to the FDA. Pfizer completed another FDA-required follow-up study last fall that found Pristiq was not more likely to cause sexual dysfunction than a placebo.

The postmarketing studies are not the only obligations for Pristiq that Wyeth left for Pfizer to fulfill. It also got saddled with some legal issues. Pfizer paid $67.5 million in 2012 to settle a class-action lawsuit with Wyeth shareholders who claimed the company had not warned them about the safety concerns of the drug. The suit was filed after a 2007 announcement that FDA wouldn't approve the company's Pristiq to treat hot flashes without more information about its safety, news that trimmed its market value by $7.6 billion in a one-day free fall.

The drug is not a blockbuster, but it has done well for Pfizer over the years. Sales were actually up 11% in 2013, before succumbing to competition in the U.S. last year and falling 6% to $723 million. Sales were down 6% in the last quarter to $161 million. Pfizer last year had to recall nearly 221,000 bottles of 50-mg Pristiq Extended Release tablets after a single 100-mg pill was found in a 50-mg bottle.

- here's the announcement