Zofran (ondansetron) has often been used to combat nausea during pregnancy.  It has never been approved by the FDA for that indication, but clinical experience has not supported an association with pregnancy-related risks – for example, a recent systematic review and meta-analysis concluded that use of ondansetron during pregnancy was associated with a reduced incidence of miscarriage but “was not associated with abnormal pregnancy outcomes,” including a variety of birth defects.  Nevertheless, plaintiffs have alleged that Zofran causes birth defects and that the warnings accompanying the drug should have said so.  Those claims were dismissed in 2021 when the district court held them preempted, and the First Circuit recently affirmed that decision in In re Zofran (Ondansetron) Products Liability Litigation, — F.4th —, 2023 WL 128570 (1st Cir. Jan. 9, 2023).

Plaintiffs in the Zofran MDL alleged, among other things, that the defendants failed to warn of birth defects observed in certain animal studies.  Because such claims implicate the warnings accompanying an FDA-approved drug, they are preempted unless the manufacturer could have unilaterally amended the label through the Changes Being Effected (CBE) regulation.  The CBE regulation permits a manufacturer to amend a product’s labeling without prior FDA approval “to reflect newly acquired information” and thereby “add or strengthen” the warnings where there is “evidence of a causal association” between the drug and the subject on which the warnings are being amended.

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