Exposure to the carcinogen NDMA produced by Zantac resulted in colon cancer, according to a lawsuit filed this week against several manufacturers of the popular heartburn drug.

The complaint (PDF) was filed by Gary Hart in the U.S. District Court for the Southern District of California on December 2, naming Boehringer Ingelheim, Sanofi US, Pfizer and GlaxoSmithKline as defendants. Each of the drug makers held rights to the Zantac brand at various times over the past few decades.

Hart indicates that he began using prescription Zantac in 2000, and took 300 mg every day through 2008. He was diagnosed with colon cancer in May 2008, and blames the development of the malignancy the active ingredient contained in Zantac, ranitidine, which it has recently been discovered may convert to high levels of N-Nitrosodimethylamine (NDMA) inside the body, increase the risk of several types of cancer along the digestive tract.

Zantac (ranitidine) has been a top selling heartburn and acid reflux drug since it was introduced in the early 1980s, but most versions have been removed from the market over the past few months, after a series of Zantac recalls were issued by different drug makers following the discovery that “unacceptable” levels of NDMA were found in all versions of the medication.

Hart indicates that the drug makes knew or should have known about the link between Zantac and colon cancer side effects, yet failed to disclose the information to consumers, doctors and regulators, continuing to market and sell the drug to millions of people.

“To be clear, this is not a contamination case—the levels of NDMA that researchers are seeing in Zantac is not the product of some manufacturing error,” Hart’s lawsuit states. “The high levels of NDMA observed in Zantac is a function of the ranitidine molecule and the way it breaks down in the human digestive system.”

In September, the online pharmacy Valisure filed a Citizens Petition with the FDA, calling for all versions of Zantac to be recalled from the market, after testing confirmed that NDMA was created due to the inherent structure of the active pharmaceutical ingredient in the heartburn drug, indicating that all users may be exposed to unacceptably high levels of the cancer-causing chemical.

Since the information was publicly released, dozens of Zantac cancer lawsuits have been filed by individuals throughout the United States, each involving similar allegations that plaintiffs developed kidney cancer, stomach cancer, bladder cancer, colorectal cancer, esophageal cancer or other cancers along the digestive tract, as ranitidine contained in Zantac broke down into NDMA inside the body.

As lawyers continue to investigate potential Zantac cancer claims over the coming months and years, it is widely expected that thousands of lawsuits will be brought throughout the federal court system.

Tags: Boehringer Ingelheim, Cancer, Colon Cancer, GlaxoSmithKline, Heartburn, Heartburn Drug, NDMA, Pfizer, Sanofi, Zantac