Federal regulators say they have identified the source of cancer-causing impurities that have tainted millions of bottles of commonly used generic blood pressure and heart failure medications recalled by drugmakers over the last seven months
The carcinogens are a chemical byproduct of the process used to synthesize the active ingredient in drugs, which include valsartan, losartan and irbesartan. People who take these drugs may have been exposed to trace amounts of impurities for at least four years, after switching into how companies manufactured the active ingredient, according to the Food and Drug Administration
An FDA statement Friday disclosed that contaminants , called N-Nitrosodimethylamine and N-Nitrosodiethylamine, are created when "specific chemicals and reaction conditions are present. . . "The agency said these byproducts would not have been detected in routine inspections because the process depends on scientists knowing which chemical intruders are likely to be accidentally created during the process, but David Light, chief executive of Valcury, an online pharmacy that chemically validates drugs before shipping them to consumers, said that it is possible that companies did not clean up the active ingredients as a cost -saving measure. "In chemistry, it's pretty easy to throw some chemicals together and get a reaction," said Light. "It's not surprising, he said, that the synthesis process would create contaminants. "What's hard to do is clean it up and only get the product you want. . . . The manufacturers know, or should have known, about the contamination. "
It remains unclear how many patients may have been exposed to carcinogens, but agency leaders have previously estimated that 1 million to 2 million
"We are making important strides in understanding how these impurities have occurred, mitigating the risk to patients and learning what steps need to be taken to prevent this from happening again in the future," Commissioner Scott Gottlieb and Center for Drug Evaluation and Research Director Janet Woodcock said in a statement. "While the total exposure to these impurities for most patients was small, we are deeply concerned that patients have been exposed to this impurity first and that the presence of nitrosamines has been undetected for a period of time."
The agency has The FDA said that if 8,000 people took the highest dose of one drug, valsartan, for four years, there could be one additional case of cancer But the official limit considered "safe" for human consumption is much lower – and would cause less than one additional case of cancer in 100,000 people over a lifetime
The unfolding investigation shines a light on the dark corners of a complex, international drug supply chain – and in particular the difficulties that can arise when generic drug issues arise, which may be made by multiple drug manufacturers and repackagers that may
The problems were first detected in drugs that traced back to active ingredient maker Zhejiang Huahai Pharmaceutical Co., in China, but were also found in drugs made from active ingredients made by Hetero Labs in India. Drug companies that sell generic medications include Mylan Pharmaceuticals, Teva Pharmaceuticals, Sandoz, Prinston Pharmaceuticals, ScieGen and Torrent Pharmaceuticals. Some of these companies also sell the drugs under different labels. For example, Prinston recalled the batches of drugs that were labeled Solco Healthcare, and Teva recalled batches labeled as made by Actavis and Major Pharmaceuticals.
Valsartan has been in a lack since August, and the agency warned in its statement that "other types of products may fall into shortage soon, "without offering any specifics. The agency is urging patients to continue taking their medications until a pharmacist or doctor provides another option because they need to balance the risks of out-of-control blood pressure against that of a tiny increased risk of cancer
An FDA spokeswoman said the investigation continues and it is impossible to predict how many more recalls might be. She said that drug manufacturers will continue to test their products and recall pills that contain impurities over an interim limit, the FDA established to ensure that patients can continue to have access to the medications in the short term
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