An independent lab has possibly identified the cause of contamination of ranitidine (Zantac) antacid products in the U.S. by the carcinogen N-nitrosodimethylamine (NDMA), after weeks of uncertainty and unfruitful lab testing. 

Since the late fall of 2019, the FDA has announced a series of voluntary recalls by manufacturers and distributors of ranitidine products in the U.S. after discovering that they had unacceptable levels of NDMA. The FDA has advised that pharmaceutical companies test their drugs after production and not release them to the U.S. market if contamination levels were high enough to expose patients to more than 96 nanograms of NDMA per day. 

First reported by Bloomberg, new testing by Emery Pharma in Alameda, California demonstrated that a combination of heat and time might be the culprit for contamination. Analysis showed that limited heat exposure would be enough to trigger a rise in NDMA levels through destabilization of the drugs. A sample of ranitidine surpassed the FDA’s 96 nanogram NDMA limit after five days at 158 degrees Fahrenheit (70 degrees Celsius), and by 12 days the sample reached 142 nanograms of NDMA. Emery Pharma also tested the drugs at a common daytime temperature of 77 degrees Fahrenheit (25 degrees Celsius), and found that a sample reached 25 nanograms over 12 days. 

The analysis by Emery suggests that anything from extended exposure to a warm ambient temperature to a long delivery in a hot truck risks increasing NDMA levels in all ranitidine products. The longer the exposure the higher the contamination levels might rise, increasing the risk that a patient might only need one or a couple doses to expose themselves to a level of NDMA substantially higher than the FDA guideline. As a result, Emery submitted a Citizen Petition to the FDA requesting a total suspension of ranitidine products, a mandatory recall of any product available on the market, stability testing on future products, temperature-controlled delivery, and new warning labels describing the risk of development of carcinogens from heat exposure.