The heartburn drug Zantac has been on the market for decades, and was considered safe enough to be sold over the counter and regularly given to infants.
But on Sept. 13, the Food and Drug Administration said that it had detected low levels of a cancer-causing chemical in samples of the drug, which is also known as ranitidine. The agency advised patients who were taking over-the-counter versions of Zantac to consider switching to other medications.
On Sept. 18, the drug maker Novartis said that its generic-drug division, Sandoz, had stopped distributing a prescription form of ranitidine worldwide as it investigates the issue. Another major generic manufacturer, Dr. Reddy’s Laboratories, also said it was halting distribution...So how did it get in there? Via Derek Lowe's post, this Pharmaceutical Technology piece might explain some of it:
Under acidic conditions, sodium nitrite forms nitrous acid, which could react with the residue of dimethylamine in dimethylformamide—the solvent that is used in the tetrazole-forming reaction—to generate NDMA, says Andre.There's definitely room for dimethylamine in the synthesis of ranitidine, but where's the nitrous acid come from? Guessing there are lots of folks from Sandoz working on that question right now....