Distribution of generic versions of the popular heartburn drug ranitidine (Zantac, Novartis) is being halted in markets worldwide by the manufacturer, according to a spokesperson for Novartis, after findings that the medication may have become tainted with a cancer-causing agent.

Dana Kahn Cooper, a spokesperson for Novartis, told Medscape Medical News: "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.”

The action was taken after regulators in the United States and Europe began investigating the discovery of a likely human carcinogen called NDMA, or N-Nitrosodimethylamine, in the medications last week, as reported by Medscape Medical News.

Ranitidine is taken by millions worldwide for gastrointestinal disorders and discomfort. Sandoz/Novartis is one of several generic drug makers that distribute it. French drug maker Sanofi makes branded Zantac sold without a prescription. Ranitidine is sold in both over-the-counter and prescription versions.

Health Canada has halted further distribution of products containing ranitidine marketed by any companies, whereas Sandoz Canada is recalling its oral prescription products. Existing stocks of ranitidine can still be sold in Canada while the agency investigates, according to a news release.

Ranitidine that is manufactured by another company, India-based Saraca Laboratories Limited, is also being recalled in some countries in the European Union, according to a statement from Germany's Federal Institute for Drugs and Medical Devices. The statement does not indicate which countries are specifically involved.

NDMA is the same impurity that fueled a recall of numerous so-called sartan blood pressure and heart failure drugs beginning last year, as reported by Medscape Medical News.

For more news, follow Medscape on Facebook, Twitter, Instagram, and YouTube.