Zeneca, Inc. v. Shalala

In 1996, the Food and Drug Administration (FDA) awarded Zeneca, Inc., three years of exclusivity for its reformulated parenteral (injectable) drug Diprivan (a form of the anesthesia propofol). The drug was reformulated to add a preservative—disodium edentate (EDTA)—to prevent microbial contamination. In 1997, Gensia applied to the FDA for an Alternative New Drug Application (ANDA) for generic propofol with EDTA, but later amended its application to substitute a sulfite preservative for EDTA. In 1998, Zenica petitioned the FDA to decline to approve any generic version of Diprivan that contained an antimicrobial other than EDTA. Zenica contended that there were no studies to support the safety of the sulfite preservative alternative and any approval of such by the FDA would violate FDA labeling regulations. On the same day in 1999, the FDA denied Zeneca’s petition and granted Gensia’s ANDA without requiring Gensia to conduct clinical studies to show the safety of its drug. Instead, to account for any risk of adverse reaction to patients with sulfite allergies, the FDA required Gensia to inform practitioners in its labeling of precautions related to the presence of sulfites and prominently display the product’s content of sulfite on its label. Zeneca sought court review and argued the FDA’s approval of Gensia’s generic propofol with the substitute sulfite preservative without requiring further testing was arbitrary and capricious.