(CNN) - Drugmaker Novartis said it is halting distribution of all ranitidine medicines made by Sandoz, a measure it called "precautionary" after the acid-reducing medications were found to contain an impurity.
The move comes after the US Food and Drug Administration and European Medicines Agency announced earlier this month that tests showed some ranitidine products contained NDMA, which is classified as a probable human carcinogen based on lab tests.
The FDA is evaluating whether the low levels of NDMA in ranitidine pose a risk to patients and said it will share the information when it is available.
Ranitidine is an over-the-counter and prescription histamine-2 blocker, which decreases the amount of stomach acid.
"A precautionary distribution stop of all Sandoz ranitidine-containing medicines in all our markets will remain in place under further clarification, this includes capsules in the USA. Our internal investigation is ongoing to determine further details. In case of concerns, adequate additional measures will be implemented in alignment with relevant Health Authorities as required," Novartis said in a emailed statement.
Drugmaker Sanofi, which makes ranitidine medication sold under the brand name Zantac, said in a statement emailed on Thursday that it currently has "no plans to stop distributing or manufacturing Zantac or other ranitidine products outside of Canada."
"The FDA reported that the levels of N-nitrosodimethylamine (NDMA) in ranitidine in preliminary tests barely exceed amounts found in common foods. We are working closely with the FDA and are conducting our own robust investigations to ensure we continue to meet the highest quality safety and quality standards," Sanofi's statement said.
The FDA has been investigating NDMA and other impurities in blood pressure and heart medicines known as ARBs since last year. Numerous recalls have been launched as the FDA found "unacceptable levels" of nitrosamines in those drugs.
The FDA says people don't need to stop taking the ranitidine medication, but patients taking the prescription versions may want to talk to their doctors about other treatment options, and people taking the over-the-counter version can consider other medicines approved for their conditions.
NDMA can cause harm in large amounts, but the levels the FDA found in preliminary tests of ranitidine "barely exceed amounts you might expect to find in common foods," according to a statement last week from Dr. Janet Woodcock, research director for FDA's Centers for Drug Evaluation and Research.
Woodcock said the agency is working with international regulators and industry partners to determine the source of the ranitidine impurity.
People can report adverse health reactions with ranitidine to the FDA's MedWatch.
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