The United States Food and Drug Administration (FDA) has issued warnings about cancer risks associated with the popular stomach acid medication Zantac. USA Today reports the FDA found unacceptable levels of the probable carcinogen NDMA, or nitrosodimethylamine while testing Zantac and its generic, ranitidine, in September.
Zantac has been routinely used by heartburn sufferers for decades, leading consumers to question how the drug became a potential carcinogen.
Zantac was prescribed more than 15 million times a year without safety concerns prior to the FDA’s announcement. The agency wants manufacturers to test and recall drugs to see if NDMA levels exceed standards. Investigations still seek to determine if Zantac and ranitidine users face greater cancer risk, but the agency said consumers might want to choose different medications. The FDA found no NDMA in over-the-counter alternatives such as Pepcid, Tagamet, Nexium, Prevacid, and Prilosec.
How did such a popular over-the-counter drug become a potential cancer risk?
The agency is still working to determine how the carcinogen is formed. FDA officials are testing samples and publishing standards for worldwide regulators and drug manufacturers. Many chemists believe that ranitidine is reacting with something else during manufacturing, finishing, or in storage. The FDA also asked pharmaceutical companies to examine if the drug’s ingredients are exposed to nitrites during manufacturing.
The FDA and independent agencies have conducted studies on ranitidine in the stomach and intestine with inconclusive results. The FDA studied how ranitidine reacts with stomach and intestine fluids and found no evidence that Zantac formed carcinogens. However, Valisure, an independent online laboratory, and pharmacy tested Zantac in stomach-like fluids with added nitrates commonly found in the body and in foods. With nitrates added, Valisure found one tablet of Zantac exceeded the FDA’s NDMA threshold 3,100 times.
Following the agency’s announcement, many retailers and drugmakers took action. Health Canada stopped distributing the drug. Sanofi, a French drugmaker, recalled the drug from retail shelves and drugstores. Germany, Italy, and Switzerland did the same. Taiwan instituted a fine for any pharmacy with ranitidine on its shelves, and Pakistan banned the drug’s distribution and manufacturing.
In the United States, eight companies pulled ranitidine from their shelves. These included pharmaceutical companies and generic ranitidine drugs from Kroger and Walgreens. Despite the voluntary recalls, the FDA took a more measured approach, asking manufacturers to recall the drugs if NDMA exceeds standards after testing.
Zantac was approved for mass markets in 1984, and researchers at Valisure said the drug’s potential risks can be found in medical studies close to its inception. Valisure CEO David Light said the risk appears to be in the drug itself, instead of as a manufacturing byproduct, and that the problem has been there since the 1980s. In a petition to the FDA, Valisure cited the 1987 study on the concerns of ranitidine conducted by Glaxo Research Group, Zantac’s original research group.
The 1987 Glaxo study examined the stomach contents of people who took Zantac. The study found no significant increase in NDMA in users, but Light claimed the study was not accurate. Light said researchers discarded stomach samples that contained ranitidine and used less accurate testing methods. Light said researchers would not find NDMA without those samples.
While researchers and other agencies seek to determine if Zantac contains unsafe levels of NDMA, the FDA extended voluntary recalls to nizatidine, a similar drug sold under the brand name Axid, if testing shows it exceeds NDMA daily limits. NDMA was also the carcinogen that led to the July 2018 recall of valsartan and losartan, two popular blood-pressure-lowering medications.
At this point in investigations, the FDA is not calling for patients to stop taking ranitidine and the agency has not requested a manufacturer recall. Some companies have voluntarily suspended Zantac sales while waiting for results from ongoing tests and research. NDMA is classified as a probable carcinogen, but it does not see that NDMA levels are high enough in Zantac to cause cancer. However, ranitidine is not recommended for long-term use and the FDA suggests patients talk to a health care professional about alternative treatment options.