The Sandoz division of pharmaceutical company Novartis AG announced it is halting global distribution of its generic versions of the heartburn medication Zantac, days after U.S. and European regulators opened an investigation into the discovery of cancer-causing chemicals in the medicine, according to Bloomberg. The halt is the latest in an ongoing movement by the U.S. Food and Drug Administration to remove contaminated drugs from the market.

Since last year, the FDA has been recalling a type of blood-pressure pill contaminated with a likely human carcinogen called NDMA, or N-Nitrosodimethylamine, thought to exclusively affect hypertension drugs. However, last Friday, the FDA and European regulators said they were also examining whether the “probable” cancer-causing chemical was in Zantac and its generic equivalent, known as ranitidine, which is taken by millions of people worldwide. Sandoz is one of several generic-drug makers that distribute it.