California Supreme Court Holds Brand-Name Drug Maker Liable to Generic Users in Terbutaline Twins Case

In September 2007, a California mother was hospitalized for preterm labor and prescribed generic terbutaline, a drug bioequivalent to Brethine, a brand-name beta-adrenergic agonist that Novartis Pharmaceuticals had originally developed. Her doctors instructed her to continue taking the drug every six hours through the 32nd week of pregnancy. She carried the pregnancy to term and gave birth to fraternal twins in October 2007.

Both children were later diagnosed with autism and developmental delays. A family member, acting as guardian ad litem, filed suit alleging that prenatal terbutaline exposure caused the neurological injuries and that Novartis had known of fetal risk but failed to update Brethine's warning label before divesting the drug in December 2001, nearly six years before the twins' mother filled her prescription.

Novartis demurred, arguing that federal drug law required generic manufacturers to copy the brand-name label verbatim, making it impossible for the generic maker to change warnings independently, and that Novartis itself bore no responsibility after transferring the New Drug Application years before any exposure occurred. The trial court sustained the demurrer without leave to amend, ruling Novartis owed no duty as a matter of law.

The Court of Appeal reversed. Thorsnes Bartolotta McGuire's Kevin Quinn and Benjamin Siminou, together with Leslie Brueckner of Public Justice, argued that the duty to warn attached to the originating label and persisted because it was foreseeable that successor manufacturers would carry forward any deficiencies without independent review. The California Supreme Court, in a 4-3 opinion issued December 21, 2017, affirmed. The court held that a brand-name drug manufacturer owes a duty of reasonable care to ensure its label carries adequate warnings regardless of whether the injured person took the branded product or a generic bioequivalent. The court further held that divestiture of the drug did not extinguish that duty where the manufacturer had reason to foresee the successor might not independently correct defective warnings.

The ruling, reported at 4 Cal.5th 145, 407 P.3d 18, established what courts call innovator liability in California, allowing plaintiffs harmed by generic drugs to pursue claims against the original brand-name developer whose label deficiencies passed downstream. The case was remanded for further proceedings.