More than 2,450 Zantac cancer lawsuits consolidated in multidistrict litigation (MDL) were dismissed by the judge presiding over the MDL, clearing manufacturers of the popular heartburn medication from liability in causing the plaintiffs’ various types of cancers.

U.S. District Judge Robin L. Rosenberg issued a 341-page ruling on Dec. 6, which stated that the plaintiffs’ attorneys failed to deliver credible scientific evidence that the active ingredient in Zantac, ranitidine, could chemically transform into a cancer-causing byproduct. Judge Rosenberg’s opinion delivered a summary judgment in favor of drug makers GlaxoSmithKline, Pfizer, Sanofi SA and Boehringer Ingelheim, Reuters reported

Judge Rosenberg took issue with the scientific evidence presented by the online, independent pharmacy and lab-testing company, Valisure, which claimed in 2019 to have “discovered the link of Zantac and its generics (ranitidine) to the carcinogen NDMA during its routine testing of every batch of every medication.” 

Valisure notified the FDA of its initial findings in June 2019. In Sept. 2019, Valisure filed a petition with the FDA that requested the agency recall all ranitidine products from the market. 

“Valisure’s research, along with that of Stanford University and others, found that N-Nitrosodimethylamine (NDMA) was the result of the ‘inherent instability’ of the ranitidine molecule,” Valisure noted in 2019, when it filed a citizens petition with the FDA. The FDA, after conducting its own testing, recalled all ranitidine-containing products from the market on April 1, 2020. 

Despite the agency’s recall, Judge Rosenberg called into question Valisure’s testing procedures that revealed that Zantac had high enough levels of NDMA to cause cancer, including heating ranitidine to temperatures much higher than inside the human body. In addition, Judge Rosenberg questioned the validity of Valisure using “excessively” high levels of sodium in its testing protocols when the drug did not contain similar levels.

Judge Rosenberg also noted that the public’s exposure to NDMA could exceed the FDA’s safe limit by consuming processed and smoked meats, yet those products remain on the market, reported.

Zantac MDL plaintiffs did not exclusively use Valisure’s data in the litigation. However, other scientific experts called by plaintiffs relied on similar evidence. Judge Rosenberg added that the only reliable way to test ranitidine places the amount of NDMA in the active ingredient at a level that is approximately the same as the FDA’s safe daily limit, which is 96 nanograms (ng). Valisure claimed that just one dose of Zantac could expose users to more than 3 million ng.

Judge Rosenberg’s dismissal also affects more than 150,000 claimants in the Zantac MDL registry. However, the order does not impact the thousands of other Zantac cancer lawsuits filed in state courts. 

Zantac lawsuits in the MDL focused on bladder, liver, pancreatic, stomach and esophageal cancer claims. Plaintiffs who alleged they developed other types of cancers because of Zantac filed their lawsuits in state courts.