The move is the latest step in an ongoing investigation into a contaminant known as N-Nitrosodimethylamine (NDMA), a chemical form of nitrosamine which is classified as a probable human carcinogen and found to be present in ranitidine.
“The agency has determined that the impurity in some ranitidine products increases over time and when stored at higher than room temperatures and may result in consumer exposure to unacceptable levels of this impurity,” the FDA said in a statement.
Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research said that the agency did not detect unacceptable levels of NDMA in many of the samples that it tested.
“However, since we don't know how or for how long the product might have been stored, we decided that it should not be available to consumers and patients unless its quality can be assured," she added.
Last summer, the FDA became aware of independent laboratory testing that found NDMA in ranitidine. It issued a warning to the public in September 2019 of the potential risks and to consider alternative OTC and prescription treatments but fell short of ordering a withdrawal.
The potential risk of nitrosamine impurities in medications has prompted a string of product recalls that have rocked the active pharmaceutical ingredient manufacturing sector over the last two years.
The FDA first said it had detected NDMA in Angiotensin II receptor blockers – commonly known as the sartans -- used to treat blood pressure back in July 2018.
The drug regulator has asked manufacturers of nizatidine and ranitidine to test their products for NDMA and send samples in. It is also conducting ongoing investigations into the presence of nitrosamine in other drug products.