Jan. 25 (UPI) -- The U.S. Food and Drug Administration has pinpointed the carcinogens that tainted many popular blood pressure medications, which could possibly lead to shortages of drugs to treat hypertension.
Early this week, the manufacturer of irbesartan, a drug treatment for high blood pressure and heart failure, recalled the drug after finding it contained cancer-causing substances.
The impurities -- known as N-Nitrosodimethylamine, or NDMA, and N-Nitrosodiethylamine, or NDEA -- may come from a chemical reaction created after the production of drugs like valsartan, losartan and irgesartan.
"As part of this continuing process, last week, we alerted patients and health care professionals to a voluntary recall of one lot of irbesartan and seven lots of irbesartan and hydrochlorothiazide (HCTZ) combination tablets," an FDA statement read.
The recalls started last summer when the FDA stopped all shipments of valsartan from China-based manufacturer Zhejiang Huahai Pharmaceuticals to the U.S.
In November, generic drugmaker Sandoz voluntarily pulled blood pressure medication losartan from the market due to contamination concerns, making it the third recall in recent weeks.
After that came another recall from generics maker Mylan Pharmaceuticals of valsartan tablets, plus combination tablets of valsartan and amlodipine and valsartan and hydrochlorothiazide.
"We've also been asked whether the FDA could have prevented this from occurring if we had done something differently during surveillance inspections in the preceding years," the statement read. "We'll continue to improve our science and standards for detecting and preventing these risks."
"We know patients rely on these medicines," the agency said. "Part of our work throughout this process has been to mitigate and prevent shortages, where possible. Currently, valsartan products are in shortage, and we know that other types of products may fall into shortage soon. That's why the agency has also evaluated safety data for NDMA and NDEA to determine interim acceptable intake levels for these impurities in the ARB class of medicines."