Plaintiffs attorneys have filed a class complaint on behalf of millions of consumers of Zoloft, alleging they were misled about the effectiveness of the prescription antidepressant drug.

The suit is the first consumer class action filed over Zoloft, one of several selective serotonin reuptake inhibitors, or SSRIs, used to treat depression and anxiety disorders, said Michael Baum, senior managing partner at Los Angeles-based Baum, Hedlund, Aristei & Goldman. Baum’s firm has filed similar consumer class actions over the drugs Paxil, Celexa and Lexapro.

"The issue of antidepressant efficacy is its inability to out-perform a placebo," Baum said. "This case is not a fraud-on-the-FDA case. It’s a claim that the prescribing doctors and patients have been misinformed or under-informed about Zoloft’s inability to outperform placebos in many trials in their advertising and labeling that went to the public and to media and to patients and physicians. They were being misled."

Zoloft has not been recalled from the market and the U.S. Food and Drug Administration, when updating the labeling of Zoloft in December, did not raise any issues relating to the drug’s efficacy.

Pfizer spokesman Steve Danehy issued an emailed statement in response to the lawsuit: "Millions of patients and their prescribers have chosen Zoloft for more than 20 years for the treatment of depression and other psychiatric conditions. They know best when the patient’s depression is being treated effectively and their continuing choice of Zoloft (or its generic form sertraline) to treat this common, but serious and potentially debilitating illness, is powerful confirmation of its safety and efficacy."

He added: "Pfizer believes the lawsuit filed in California is groundless and is based largely on information first published over three years ago that has been widely criticized by many experts in the mental health field. Moreover, plaintiffs in this putative class action seek refunds for Zoloft, even though FDA approved the medicine for the treatment of depression and their physicians prescribed it for this same purpose, under a legally unsupportable theory that FDA never should have approved the medicine."

Baum’s firm has been actively involved in related litigation over birth defects and suicide attributed to Zoloft. The use of Zoloft also has been cited in criminal trials, with defendants arguing that the drug caused them to act impulsively.

Baum said he was prompted to file the suit after obtaining internal documents from Pfizer in the suicide litigation and following a 60 Minutes episode last year featured Irving Kirsch, associate director of the Program in Placebo Studies at Harvard Medical School, who questioned the efficacy and clinical studies of the drugs.

In the suit, filed on January 30 in the Northern District of California, Laura Plumlee of Santa Cruz County, Calif., claims she began taking Zoloft for depression in 2005. Her doctor increased her dosage from 50 mg. to 400 mg. per day after she showed no signs of improvement. She switched to Zoloft’s generic equivalent in 2006 and continued to take that medication until 2008.

"Pfizer knew that Zoloft’s efficacy in treating depression was, at best, marginal and, at worst, nonexistent," the suit says. "However, in an effort to turn a profit, Pfizer deliberately withheld material information from consumers and prescribing healthcare professionals and orchestrated a massive marketing campaign designed to convince consumers and prescribing healthcare professionals, in the face of the vast majority of clinical trial data to the contrary, that Zoloft was an effective and safe treatment for depression."

The suit alleges that of the six clinical trials submitted to the FDA for approval to sell the drug, only two showed any relief of depression. Pfizer’s labeling of Zoloft fails to note the other four clinical trials, the suit says. "By selectively publishing clinical trial data, Pfizer has been able to convince the public and the medical community that Zoloft is more effective than clinical trials indicate."

Danehy addressed the science behind the clinical trials. "Zoloft was first approved by the FDA in 1991 based on the agency’s review of the efficacy and safety data from more than 20 clinical studies involving more than 5,000 patients," he wrote. "There is extensive science supporting the safety and efficacy of Zoloft and the medicine carries accurate, science-based and FDA approved information on its benefits and risks."

The class includes consumers who purchased Zoloft from December 30, 1991, to the present. They seek a declaratory judgment preventing Pfizer from continuing to use the same labeling for Zoloft. The class also includes California consumers seeking refunds and statutory damages under California’s unfair business practices and false advertising laws.

Contact Amanda Bronstad at abronstad@alm.com.