As regulators and researchers around the world rush to determine if Zantac poses a cancer risk, a new report indicates the potential danger was recognized as early as the 1980s.
Drug makers have been recalling name-brand and generic versions of Zantac since September 13th, when the U.S. Food & Drug Administration (FDA) warned that tests had detected N-Nitrosodimethylamine, or NDMA, in some samples of ranitidine-containing heartburn medications.
NDMA is considered a probable human carcinogen, and has been linked to an increased risk of kidney, liver, and gastrointestinal cancers.
The FDA was informed of the findings by Valisure, an online pharmacy that said it detected NDMA in every sample of Zantac and ranitidine it tested, and often at levels that far exceeded the agency’s recommended daily limits. Valisure also suggested the NDMA was the result of the unstable ranitidine molecule, which the company’s tests indicated degrades when subjected to conditions similar to human digestion.
According to USA Today, the FDA has since tested 1,500 Zantac and ranitidine samples. While the agency found lower levels of NDMA compared to Valisure, levels still exceeded the FDA’s daily limits in many cases.
At this time, the agency does not believe ranitidine produces NDMA in the stomach, but concedes that the ranitidine molecule is likely producing the potentially cancer-causing chemical.
“Our chemists believe that it is formed by the molecule ranitidine reacting with something, either during the manufacturing synthesis or during the finished dosage form or during storage,” Janet Woodcock, director of the FDA’s Center for Drug Evaluation and Research, told a congressional committee late last month.
Unlike the FDA’s tests, however, Valisure’s testing exposed Zantac to stomach fluids with and without added nitrites, chemicals commonly found in foods and the body.
“Ingesting nitrite-containing foods like hot dogs can significantly increase stomach levels of nitrite,” Valisure CEO David Light told USA Today. “These foods are often eaten by individuals either before or after taking antacid products.
Apparently, this isn’t a new issue with Zantac. In fact, studies conducted in the 1980s raised similar concerns. Those findings caused GlaxoSmithKline, the original manufacturer of Zantac, to conduct its own study, which found no significant increase in nitrosamines such as NDMA within 24 hours of taking ranitidine.
But Valisure’s Light contends that Glaxo’s tests were less accurate and that researchers discarded stomach samples that contained ranitidine. Without those samples, the tests wouldn’t detect NDMA and other nitrosamines.
“The negative affect of exposure to this drug and its formation of NDMA is something that has created a huge public health problem,” Light said, “and we’re going to be dealing with it going forward.