Drug regulators in the United States and Europe are investigating medicines that contain ranitidine (multiple brands) for the presence of the probable carcinogen N-nitrosodimethylamine (NDMA), the same impurity that fueled a recall of numerous so-called sartan blood pressure and heart failure drugs beginning last year.

Ranitidine is an over-the-counter (OTC) and prescription histamine-2 blocker that decreases the production of stomach acid. OTC ranitidine is approved for prevention and relief of heartburn. Prescription ranitidine is approved for multiple indications, including treatment and prevention of ulcers of the stomach and intestines and treatment of gastroesophageal reflux disease.

The US Food and Drug Administration (FDA) said today that some medicines containing ranitidine have been found to contain low levels of NDMA, and the agency is evaluating whether this poses a risk to patients.

"Although NDMA may cause harm in large amounts, the levels the FDA is finding in ranitidine from preliminary tests barely exceed amounts you might expect to find in common foods," Janet Woodcock, MD, director of the FDA's Center for Drug Evaluation and Research, said in a statement.

The European Medicines Agency (EMA) announced today that it would start a review of ranitidine medicines after tests revealed NDMA in some products. The review was requested by the European Commission.

Woodcock said the FDA is working with international regulators and industry partners to determine the source of this impurity in ranitidine and would provide an update as more information becomes available.

For now, the FDA is not calling for people to stop taking ranitidine. They advise patients who are taking prescription ranitidine and who wish to discontinue use of the drug to talk to their healthcare professional about other treatment options. "People taking OTC ranitidine could consider using other OTC medicines approved for their condition," the FDA said. The EMA is offering similar advice at this time.

The FDA and the EMA have been investigating NDMA and other nitrosamine impurities in angiotensin II receptor blockers (ARBs), and several companies have announced recalls because of contamination, as reported by Medscape Medical News.

The FDA keeps a running list of recalled ARB products, including valsartan (multiple brands), losartan (Cozaar, Hyzaar, both from Merck Sharp & Dohme), and irbesartan (Avalide, Avapro, both from Sanofi-Aventis).

In April, the agency published a list of 40 ARBs it had determined were free of contamination from nitrosamines, as reported by Medscape Medical News.

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