FDA: Some Tainted Losartan Must Remain on US Market to Maintain Adequate Access for Patients

Despite the presence of probable carcinogens, the US Food and Drug Administration says it will allow certain manufacturers to continue distributing losartan to ensure adequate patient access to the drug until a supply that is free of impurities becomes available later this year.

In a statement issued on March 20, 2019, the agency said losartan containing levels of N-Nitroso-N-methyl-4-aminobutyric acid (NMBA) that exceeds the interim acceptable intake limit of 0.96 ppm, but is below 9.82 ppm, “will help maintain adequate losartan supply while companies obtain approval for manufacturing processes that produce nitrosamine-free losartan for patients.” NMBA is known to be an animal carcinogen and potentially a human one as well.

According to the statement, the agency “expects many companies will be able to manufacture losartan without nitrosamine impurities and replenish the US supply in approximately 6 months.” It goes on to note that FDA scientists “evaluated the risk of exposure to NMBA at levels up to 9.82 ppm and determined that it presents no meaningful difference in cancer risk over a 6-month time period when compared to a lifetime of exposure to NMBA at 0.96 ppm.”

Concern over tainted angiotensin-receptor blockers was first raised last summer when the FDA announced that some generic tablets contained nitrosamine impurities that did not meet the agency’s safety standards.

That announcement was followed by a flurry of recalls in July to pull valsartan products contaminated with N-Nitrosodimethylamine (NDMA). In August, the list of affected valsartan products was expanded. Another nitrosamine, N-Nitrosodiethylamine (NDEA), was subsequently identified first in irbesartan tablets, then additional valsartan-containing medications. This week, just 1 day before the FDA announced that it would allow the tainted losartan from certain manufacturers to remain on the market, Legacy Pharmaceutical Packaging, LLC, issued a voluntary recall of 40 repackaged lots their losartan tablets due to the detection of trace amounts of NMBA.

The FDA says it will determine, on a case-by-case basis, which lots of losartan containing NMBA that exceeds the 0.96 ppm limit will be released for distribution.