(Adds Pfizer comments, Zoloft details, case citation, byline)
June 2 (Reuters) - Pfizer Inc on Friday defeated an effort to revive more than 300 lawsuits alleging that its antidepressant Zoloft causes cardiac birth defects in children when taken by women during early pregnancy.
A panel of the 3rd U.S. Circuit Court of Appeals in Philadelphia upheld the April 2016 dismissal of the cases by a lower court judge, who said the plaintiffs had not shown a plausible scientific link between Zoloft and the birth defects.
The plaintiffs accused New York-based Pfizer of downplaying the risks to boost sales of Zoloft, which topped $3 billion annually before sales of generic versions began in 2006.
They sought to offer testimony from Nicholas Jewell, a biostatistics professor from the University of California at Berkeley, to establish a link between the drug and the birth defects, but the appeals court found his methods unreliable.
"Courts are supposed to ensure that the testimony given to the jury is reliable and will be more informative than confusing," Circuit Judge Jane Roth wrote for the three-judge panel. "Dr. Jewell's application of his purported methods does not satisfy this standard."
The plaintiffs conceded that they could not win without Jewell's testimony, the appeals court said in a footnote.
Lawyers for the plaintiffs did not immediately respond to requests for comment.
In an email, Pfizer said the decision "affirms the important role courts have in ensuring that only reliable scientific evidence" is introduced. Pfizer also said "extensive science" supports the safety and efficacy of Zoloft.
The birth defect lawsuits accounted for roughly half of the nearly 700 cases filed in nationwide product liability litigation over Zoloft. Others alleged non-cardiac symptoms.
Zoloft is part of a popular group of antidepressants known as selective serotonin reuptake inhibitors, or SSRIs. Sales totaled $304 million last year.
Friday's decision upheld rulings by U.S. District Judge Cynthia Rufe in Philadelphia.
The case is In re: Zoloft (Sertraline Hydrochloride) Products Liability Litigation, 3rd U.S. Circuit Court of Appeals, No. 16-2247. (Reporting by Jonathan Stempel in New York; Editing by Bernadette Baum and Steve Orlofsky)