In a statement published on August 28th, the FDA says that the cancer risk from contaminated angiotension II receptor blockers due to nitrosamine contamination is likely to be less than previously estimated. The agency also advises doctors and their patients to consider those risks against the benefits and the dangers of untreated hypertension and resultant heart failure.
Over the past several months, traces of various nitrosamines, including NDMA, have been discovered in certain lots of ARB medications such as valsartan, losartan, and irbesartan. Nitrosamines are a group of industrial chemicals used in lubricants and aviation fuel; they can also be found in smoked meats and tobacco fumes. Most of the contamination has been traced back to manufacturing plants in China and India. Recently, the FDA issued a warning letter to an Indian company where solvents used in the manufacturing process are recovered and recycled. In the letter, sent following an inspection of the facilities, Lantech Pharmaceuticals was told that their process was likely to have contributed to nitrosamine contamination.
Dr. Janet Woodcock, head of the FDA’s Center for Drug Evaluation and Research, recommends that patients speak with their health care provider if they have concerns about their medications. “The risks of stopping an ARB product for treating high blood pressure and heart failure greatly outweighs the potential risk of exposure to trace amounts of nitrosamines,” she says.
Originally, the FDA estimated that out of 8,000 patients taking the maximum dose of 320 milligrams of a contaminated ARB each day over a four-year period, there might be one additional case of cancer in over the patients’ lifetimes. However, that estimate was based on a worst-case scenario; in reality, most patients took far less than that amount. Furthermore, not all ARB drugs have been contaminated, and most of the patients who received affected products have turned them in. “Since not all ARBs are affected, it is very likely that a patient taking an ARB for 4 years would not have always received one of the affected products,” Woodcock says.
Physicians and patients who are concerned about nitrosamine-contaminated ARB medications are advised to consult the FDA’s list of contaminated lots in order to determine which products are affected. Based on laboratory tests, the FDA has been able to identify 43 ARBs in which no nitrosamines have been detected. “Ultimately, our goal is to be certain that no ARBs with unacceptable purity levels reach patients,” Woodcock says. It is hoped that new inspection methods will be able to detect problems with drugs before they reach the market going forward.