With this week's revelations of NDMA contamination in the popular antacid Zantac (ranitidine), health authorities and scientists are asking just how it happened. Frighteningly, there is evidence to suggest that it may have been there all along.
In response to the recent discovery, Zantac's original maker, GlaxoSmithKline, has suspended all shipments to pharmacies and issued a voluntary recall in India and Hong Kong (the GSK brand version is not available in the U.S.).
Novartis has recalled its generic version after it suspended shipments of the drug. Health authorities in Canada and France have instructed all drugmakers to stop distributing ranitidine altogether as Apotex, Inc., a Canadian drug company, has issued its own recall. Dr. Reddy's Laboratories Ltd., an India-based company that manufactures the active ingredient in Zantac, has also stopped all shipments.
According to David Light, CEO of the Connecticut-based pharmacy Valisure, where the contamination was first discovered, NDMA may be part of the drug's molecular structure. After NDMA contamination was discovered, scientists at Valisure performed tests simulating the way ranitidine breaks down in a patient's system after taking it.
What they discovered was disturbing: it appears that one of the body's own enzymes interacts with ranitidine in such a way that releases NDMA. Light says company data indicates a “very strong scientific story that the drug itself is very unstable...this appears to be a fundamental problem with the molecule itself.”
Valisure's findings have been confirmed by studies carried out at Stanford University and elsewhere. Valisure also submitted a “Citizen's Petition” to the FDA, asking that it issue a recall. In response, the FDA said, “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.”
Light says, “There's no acceptable cancer risk for a drug like this.” Indeed: whereas NDMA levels in ARB medications were found to be up to 17 micrograms per pill, the levels detected in ranitidine pills were as high as 3,000 micrograms.
Zantac, an H2 receptor antagonist, is one of the most popular and frequently-prescribed medications in the world. Approximately 15 million people per year in the U.S. take it on a regular basis. Light's concerns about how NDMA may simply be an integral part of Zantac's chemical composition brings up a serious question, which will be asked in litigation going forward: just what did the original drugmaker know – and why did it fail to warn patients?