Thousands of consumers who sued makers of the popular heartburn drug Zantac, alleging it caused them to develop cancer, failed to present a reliable scientific basis for their claims, a U.S. District Court judge in Florida said when she dismissed their lawsuits last week. In 2020, the Food and Drug Administration requested recalls of the product after research found its original active ingredient, ranitidine, could over time and in certain storage conditions develop unsafe levels of an impurity, the compound N-Nitroso dimethylamine, categorized as a probable human carcinogen. (Zantac’s makers switched out the compound that year.) But Judge Robin Rosenberg said experts hired by the plaintiffs did not establish that ranitidine causes cancer. The pharmaceutical giants GSK, Pfizer, and Sanofi, which have made Zantac, were among the defendants in the more than 50,000 claims covered by her ruling. The decision does not directly affect thousands more such lawsuits in state courts.