The Food and Drug Administration said on Tuesday that it had approved a new generic version of the widely used blood pressure drug Diovan, or valsartan, which has been in short supply following recalls made because of chemical contamination.
The new version is being made by Alkem Laboratories Limited, based in Mumbai, India.
“The F.D.A. prioritized the review of this drug application to help relieve the recent shortage of this critical medicine as a result of multiple recalls of generic valsartan products from several manufacturers,” the agency said in a statement.
The recalls began in July when the F.D.A. found that some valsartan products contained a potentially cancer-causing chemical, a type of nitrosamine called N-nitrosodimethylamine, or NDMA. European regulators had already made the same discovery. The substance can form during manufacturing if the chemical reactions used to make the drug are not carefully controlled and monitored, the F.D.A. said.
Nitrosamines can cause tumors in the liver and other organs in lab animals and are thought to be carcinogenic in humans as well.
After several recalls of valsartan and related drugs, patients faced shortages of the popular medicine and in some cases, much higher prices as companies appeared to take advantage of the situation, according to reports.
The tainted valsartan came from a Chinese manufacturer, Zhejiang Huahai Pharmaceutical Company. Three companies distributed it in the United States: Major Pharmaceuticals; Teva Pharmaceutical Industries; and Solco Healthcare, which is owned by Huahai Pharmaceutical.
Further investigation found the same type of impurities in two other blood pressure drugs in the same class as valsartan: irbesartan and losartan. Two more nitrosamines, nitrosodiethylamine, or NDEA, and N-Nitroso-N-methyl-4-aminobutyric acid, or NMBA, were found to have impurities. Lists of the affected products are posted on the F.D.A. website. Other manufacturers were involved.
The F.D.A. said that the contaminants “are of special concern to global regulators because, unlike most impurities in drugs, they have the potential to cause harm at very low levels.”
The tainted drugs belong to a class called angiotensin II receptor blockers, or ARBs. They can treat heart failure as well as high blood pressure.
The F.D.A. said that not all lots of valsartan, irbesartan and losartan were affected and not all were being recalled. The agency said consumers should check the labels on their prescription bottles and consult the F.D.A. website for lists of the recalled products, and even if theirs is on the list, should keep taking their medicines until they can get replacements.
A statement on the F.D.A. website explained the degree of risk: “Our scientists estimate that if 8,000 people took the highest daily valsartan dose (320 mg) that contained NDMA, for four years (the amount of time we believed the affected products had been on the U.S. market), there may be one additional case of cancer beyond the average cancer rate among Americans. Most patients who were exposed to the impurity through the use of affected valsartan received less exposure than in the scenario described above.”
The F.D.A. said it was continuing to evaluate other drugs in that class “to ensure they are free of impurities.”