Zoloft. (Photo: Wikimedia Commons.)

Plaintiffs have not met their burden of establishing the reliability and admissibility of the opinions of one of their experts in multidistrict litigation over whether the antidepressant Zoloft causes birth defects, Pfizer Inc. said in court papers.

The briefing has gone through three rounds on the admissibility of Anick Bérard’s testimony, starting with Pfizer’s motion to exclude the proposed expert, with the plaintiffs’ response and now with the drugmaker’s response. Bérard is a perinatal epidemiologist who studies babies’ exposure to drugs before they are born.

Pfizer argues that there is no class effect for selective serotonin re-uptake inhibitors, so data about other antidepressants should not be included in Bérard’s analysis.

“Plaintiffs ignore altogether multiple other methodological infirmities in Dr. Bérard’s report,” Pfizer counsel Sheila Birnbaum, Mark Cheffo, Bert Wolff and Jonathan Tam of Quinn Emanuel Urquhart & Sullivan said. “For example, plaintiffs do not address the many statements that Dr. Bérard made to her peers in the scientific community that are flatly inconsistent with the for-litigation opinions she proffers here—including her peer-reviewed statements that Zoloft should be used as a first-line therapy during pregnancy.

“Plaintiffs do not address the fact that Dr. Bérard’ has no plans to subject her opinions in this case to peer-review and publication or that her report does not meet the standards of a systematic review,” Pfizer’s lawyers said.

The plaintiffs also were not able to identify any regulatory agency, published study or peer-reviewed medical treatise that concludes that Zoloft causes any of the birth defects listed in Bérard’s report, the defendant argues.

Amaris Elliott-Engel is a contributing writer for law.com.