Sweeping recalls of a class of high blood pressure drugs known as ARBs, or angiotensin II receptor blockers, has resulted in a shortage, Food and Drug Administration (FDA) Commissioner Dr. Scott Gottlieb and FDA director of drug evaluation and research Dr. Janet Woodcock said in a joint statement. And the problem will probably get worse.
The shortage is among ARBs that contain the active drug ingredient valsartan, and may soon also affect other ARBs that contain losartan and irbesartan. The shortage is due to recalls of the drug over an unexpected impurity, which was identified as a chemical called NDMA and considered a possible carcinogen.
The FDA’s ongoing investigation into the issue has concluded that the impurities were generated during the manufacturing process and could have resulted from the reuse of materials like solvents. Since the issue was identified last summer, the FDA has placed one China-based company, Zhejiang Huahai Pharmaceuticals, on an import alert, forbidding all active pharmaceuticals and finished products made by the company from entering the United States.
The FDA said it is trying to “balance the risk of patients ingesting low levels of the impurities (below the interim acceptance levels) for a short period of time with the risk that there is a shortage of certain ARBs, which may impact patients’ ability to access the medicine they need.”
It is still unknown what the long-term risks of NDMA are, but Dr. Erin Michos, an associate professor and associate director of preventive cardiology at Johns Hopkins Medicine told CNN that “the dose makes the poison.” In other words, higher doses would pose the greatest risks.
“What we know about the dangers of this impurity comes primarily from laboratory students,” she told CNN. “It is a toxin that can affect the liver and cause liver fibrosis or scarring and liver tumors in rats. So it is assumed to be toxic to humans as well.”