More than two weeks after the U.S. Food & Drug Administration (FDA) warned of the presence of a cancer-causing chemical in Zantac and other ranitidine-containing antacids, the agency acknowledge that “early, limited testing” did turn up unacceptably high levels in some samples.
The agency issued its initial warning after the online pharmacy Valisure informed the FDA that it had detected N-nitrosodimethylamine (NDMA) in every sample of ranitidine and Zantac it tested. The company also asserted that the levels detected in some samples were well above the agency’s established daily limits, and suggested the presence of NDMA was due to the instability of the ranitidine molecule, which purportedly degrades when subjected to conditions created by digestion.
In an update issued yesterday, the agency indicated it had observed the testing method employed by a third party – presumably Valisure. That method utilizes high temperatures, which actually generated NDMA from ranitidine.
Despite confirming Valisure’s findings, the FDA has yet to order a Zantac recall. In fact, the agency advised drug makers to employ a different testing method that uses lower temperatures. That method has also detected NDMA in samples of Zantac and ranitidine, but at much lower levels.
Valisure agreed that the higher temperatures employed by its tests likely generated high levels of NDMA. However, the company reiterated that a separate analysis involving conditions similar to the human stomach generated over 300,000 nanograms of NDMA, significantly higher than the FDA’s daily limits.
According to David Light, Valisure’s chief executive, this suggests ranitidine will generate NDMA in a person’s stomach after pills are ingested.
“Our feeling is that this is extremely troublesome,” he told The New York Times last month. “We took it off our formulary right away.”
The Environmental Protection Agency (EPA) considers NDMA a probable human carcinogen, as animal tests indicate exposure may increase the risk for cancer, especially tumors of the liver, gastrointestinal tract, and kidneys. Overexposure to NDMA can cause jaundice, nausea, fever, vomiting, abdominal cramps and dizziness, while contact with high levels can harm the kidneys and lungs.
The FDA has advised consumers who use over-the-counter Zantac and ranitidine products to consider switching to another antacid. Those taking prescription versions should not stop treatment without first talking with their doctor, as doing so could worsen their condition.
Last month, Novartis halted distribution of ranitidine products marketed by its Sandoz, Inc. unit. The company later recalled prescription versions after its own testing confirmed unacceptable levels of NDMA.
GlaxoSmithKline, the original manufacturer of Zantac, no longer sells ranitidine products in the United States, but did suspend distribution. Dr. Reddy’s Laboratories and Apotex are removing their ranitidine drugs from global market, while Wal-Mart, Walgreens, CVS, and Rite-Aid have pulled the medications from their store shelves.
Sanofi-Aventis, which markets name-brand Zantac, suspended distribution in Canada following a request from regulators. But the company has not moved to do so in the United States, and indicated it had no plans to issue a Zantac recall.