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GSK was warned repeatedly about Zantac impurity but played down risks: Bloomberg

Facing tens of thousands of lawsuits over cancer risks on the popular heartburn drug Zantac, GSK has argued there’s “no consistent or reliable evidence” that the medicine causes cancer. But a new report in Bloomberg Businessweek says GSK’s own scientists have long known about the drug’s risks.

Wednesday, the publication reported that over the span of multiple decades, GSK was warned by its own scientists and independent researchers about a potential cancer-causing impurity in the drug. The FDA considered the risks when it reviewed the drug, but the agency ultimately approved Zantac, or ranitidine, in 1983.

Over the years, GSK supported “flawed research” aimed at downplaying risks, and it opted against making any changes to its supply chain or storage procedures that might’ve mitigated the issue, Businessweek reports. The team reviewed “thousands of pages,” including court filings and studies, to report the story.

Intense public scrutiny on Zantac started in 2019, when an online pharmacy found high levels of a likely carcinogen in the drug and its generics. Recalls followed, and the FDA pulled the drug from the market in 2020.

In doing so, the FDA said the amount of the likely carcinogen in the drug, N-Nitrosodimethylamine, increases “even under normal storage conditions.” The problem is exacerbated by storage at higher temperatures, the FDA said.

According to Businessweek, GSK’s leadership was warned on several occasions about the storage issue, but it opted against making any changes to existing plans.

A GSK spokesperson said the article “presents an incomplete and biased presentation of the facts surrounding the Zantac (ranitidine) litigation.”

“Patient safety is the highest priority for GSK, and the company categorically refutes any allegation of having covered up data regarding the safety of ranitidine,” she said via email. “The safety of ranitidine has been thoroughly evaluated over the past 40 years.”

Nowadays, GSK and other drugmakers face tens of thousands of lawsuits centered on the drug. The companies have argued that the science doesn’t support plaintiffs’ arguments.

In a major win for the companies late last year, a judge in Florida tossed a large group of federal court cases against the companies. The judge concluded that the plaintiff’s experts utilized “unreliable methodologies” to reach their conclusions.

At the time, GSK said it was glad “litigation-driven science did not enter the federal courtroom.”

Zantac manufacturers still face more than 70,000 state court cases, Businessweek reports. That figure includes defendants who marketed Zantac after GSK sold the rights, plus generic manufacturers.

GSK’s shares were down about 2% after Businessweek’s story published on Wednesday.