GSK Plc (NYSE:GSK) has been reportedly sued by an independent Connecticut laboratory, Valisure, accusing the pharmaceutical giant of defrauding the U.S. government and taxpayers by concealing cancer risks associated with Zantac, once a blockbuster heartburn drug.  Related: Pfizer Agrees To Settle Over 10,000 Lawsuits About Cancer Risks Associated With Discontinued Heartburn Drug Zantac. In a whistleblower complaint filed on Monday, Valisure claimed GSK violated the federal False Claims Act by hiding these risks for nearly four decades while Medicare, Medicaid, and other health programs covered billions of dollars in prescriptions. Valisure's 2019 testing revealed that Zantac, also known as ranitidine, could form a ...