A recall of common blood pressure medication losartan has been expanded for a fifth time after manufacturer Torrent Pharmaceuticals found a possibly carcinogenic impurity in more batches of the drug, federal health officials said.
Three additional lots of losartan potassium tablets and two additional lots of losartan potassium/hydrochlorothiazide tablets were under recall, the U.S. Food and Drug Administration said Thursday.
The lots contained levels of N-Nitroso-N-methyl-4-aminobutyric acid (NMBA) above the acceptable daily intake levels determined by the FDA. NMBA is a "potential human carcinogen," the FDA says.
The recall comes amid a larger string of recalls of blood pressure medications valsartan, losartan and irbesartan that contain trace levels of carcinogens NMBA, N-Nitrosodimethylamine (NDMA) and N-Nitrosodiethylamine (NDEA), the FDA says.
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Hundreds of lots of the medication have been recalled since last July.
The drugs, angiotensin II receptor blockers (ARBs), work by widening or relaxing blood vessels, thus lowering blood pressure. However, not all ARBs have been affected, and patients should continue to use their medication, the FDA says.
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"The risk of harm to the patient's health may be higher if the treatment is stopped immediately without any alternative treatment," federal health officials wrote in a statement.
The FDA has said the contaminants likely resulted from a manufacturing change adopted by factories in China and India that make the drug ingredients. The manufacturing change may generate the contaminants "when specific chemicals and reaction conditions are present" and can result of reusing materials such as solvents.
In January, the agency admitted that some versions of the drug valsartan contained trace amounts of a carcinogen for four years before regulators detected the impurity last summer.
However, FDA officials said the cancer risk for any person who took valsartan that had the carcinogen N-nitrosodimethylamine, or NDMA, is small. FDA scientists concluded there would be one more cancer case above average rates for every 8,000 people on the highest dose of valsartan for four years.
Contributing: Ken Alltucker. Follow USA TODAY's Ryan Miller on Twitter @RyanW_Miller
This article originally appeared on USA TODAY: Losartan recall: FDA says more blood pressure medicine has cancer risk